16978491 has 20 divisors (see below), whose sum is σ = 25491312. Its totient is φ = 11261808.

The previous prime is 16978487. The next prime is 16978513. The reversal of 16978491 is 19487961.

It is a happy number.

It is not a de Polignac number, because 16978491 - 2² = 16978487 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16978411) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 20905 + ... + 21701.

Almost surely, 2^16978491 is an apocalyptic number.

16978491 is a deficient number, since it is larger than the sum of its proper divisors (8512821).

16978491 is an equidigital number, since it uses as much as digits as its factorization.

16978491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1072 (or 1063 counting only the distinct ones).

The product of its digits is 108864, while the sum is 45.

The square root of 16978491 is about 4120.4964506719. The cubic root of 16978491 is about 257.0196707579.

The spelling of 16978491 in words is "sixteen million, nine hundred seventy-eight thousand, four hundred ninety-one".