15640491 has 8 divisors (see below), whose sum is σ = 20874240. Its totient is φ = 10416872.

The previous prime is 15640481. The next prime is 15640517. The reversal of 15640491 is 19404651.

It is a happy number.

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 15640491 - 2⁹ = 15639979 is a prime.

It is not an unprimeable number, because it can be changed into a prime (15640441) 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, 2506 + ... + 6128.

It is an arithmetic number, because the mean of its divisors is an integer number (2609280).

Almost surely, 2^15640491 is an apocalyptic number.

15640491 is a deficient number, since it is larger than the sum of its proper divisors (5233749).

15640491 is a wasteful number, since it uses less digits than its factorization.

15640491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5065.

The product of its (nonzero) digits is 4320, while the sum is 30.

The square root of 15640491 is about 3954.8060635131. The cubic root of 15640491 is about 250.0825913783.

The spelling of 15640491 in words is "fifteen million, six hundred forty thousand, four hundred ninety-one".