16491 has 8 divisors (see below), whose sum is σ = 23040. Its totient is φ = 10472.

The previous prime is 16487. The next prime is 16493. The reversal of 16491 is 19461.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 16491 - 2² = 16487 is a prime.

16491 is a lucky number.

It is a nialpdrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (16493) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51 + ... + 188.

It is an arithmetic number, because the mean of its divisors is an integer number (2880).

2¹⁶⁴⁹¹ is an apocalyptic number.

16491 is the 69-th nonagonal number.

16491 is a deficient number, since it is larger than the sum of its proper divisors (6549).

16491 is a wasteful number, since it uses less digits than its factorization.

16491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 265.

The product of its digits is 216, while the sum is 21.

The square root of 16491 is about 128.4172885557. The cubic root of 16491 is about 25.4535872397.

The spelling of 16491 in words is "sixteen thousand, four hundred ninety-one".