TheAlgorithms/Python · error · ValueError

Only positive numbers are accepted

Error message

Only positive numbers are accepted

What it means

number_of_divisors() counts divisors via factorization. Divisor count is only defined for positive integers, so n <= 0 raises ValueError('Only positive numbers are accepted').

Source

Thrown at maths/basic_maths.py:48

        pf.append(n)
    return pf


def number_of_divisors(n: int) -> int:
    """Calculate Number of Divisors of an Integer.
    >>> number_of_divisors(100)
    9
    >>> number_of_divisors(0)
    Traceback (most recent call last):
        ...
    ValueError: Only positive numbers are accepted
    >>> number_of_divisors(-10)
    Traceback (most recent call last):
        ...
    ValueError: Only positive numbers are accepted
    """
    if n <= 0:
        raise ValueError("Only positive numbers are accepted")
    div = 1
    temp = 1
    while n % 2 == 0:
        temp += 1
        n = int(n / 2)
    div *= temp
    for i in range(3, int(math.sqrt(n)) + 1, 2):
        temp = 1
        while n % i == 0:
            temp += 1
            n = int(n / i)
        div *= temp
    if n > 1:
        div *= 2
    return div


def sum_of_divisors(n: int) -> int:

View on GitHub (pinned to f5988cc097)

Solutions

1. Start loops at 1 (range(1, n + 1)) when enumerating candidates.
2. Validate n > 0 at the input boundary.
3. Special-case 0 explicitly if your domain needs it, since the library will not.

Example fix

# before
for i in range(0, 101):
    d = number_of_divisors(i)  # fails at i=0

# after
for i in range(1, 101):
    d = number_of_divisors(i)

if n <= 0:
    raise ValueError(f"n must be positive, got {n}")
count = number_of_divisors(n)

def is_positive_int(n: object) -> bool:
    return isinstance(n, int) and n > 0

When it happens

Trigger: number_of_divisors(0); number_of_divisors(-10); any range iteration that includes 0, e.g. loop over range(0, n) calling the function.

Common situations: Iterating over sequences that start at 0; accepting negative user input; reuse of the same n across several basic_maths functions where 0 slipped through.

Related errors

• Input must be positive
• Only positive integers have prime factors
• Limit for the Catalan sequence must be ≥ 0
• Number should not be negative.
• Negative arguments are not supported

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/3901600e8a731281. Report an issue: GitHub.