15664491 has 6 divisors (see below), whose sum is σ = 22626500. Its totient is φ = 10442988.

The previous prime is 15664487. The next prime is 15664529. The reversal of 15664491 is 19446651.

15664491 is a `hidden beast` number, since 1 + 5 + 6 + 644 + 9 + 1 = 666.

It is not a de Polignac number, because 15664491 - 2² = 15664487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15664421) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 870241 + ... + 870258.

Almost surely, 2^15664491 is an apocalyptic number.

15664491 is a deficient number, since it is larger than the sum of its proper divisors (6962009).

15664491 is a wasteful number, since it uses less digits than its factorization.

15664491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1740505 (or 1740502 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 15664491 is about 3957.8391831907. The cubic root of 15664491 is about 250.2104414745.

The spelling of 15664491 in words is "fifteen million, six hundred sixty-four thousand, four hundred ninety-one".