15491 has 4 divisors (see below), whose sum is σ = 17712. Its totient is φ = 13272.

The previous prime is 15473. The next prime is 15493. The reversal of 15491 is 19451.

15491 = T₆₃ + T₆₄ + ... + T₆₉.

15491 = 44² + 45² + ... + 50².

15491 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19451 = 53 ⋅367.

It is not a de Polignac number, because 15491 - 2⁶ = 15427 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 7.

It is not an unprimeable number, because it can be changed into a prime (15493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1100 + ... + 1113.

It is an arithmetic number, because the mean of its divisors is an integer number (4428).

2¹⁵⁴⁹¹ is an apocalyptic number.

15491 is a deficient number, since it is larger than the sum of its proper divisors (2221).

15491 is an equidigital number, since it uses as much as digits as its factorization.

15491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2220.

The product of its digits is 180, while the sum is 20.

The square root of 15491 is about 124.4628458617. The cubic root of 15491 is about 24.9283280550.

The spelling of 15491 in words is "fifteen thousand, four hundred ninety-one".