16978421 has 16 divisors (see below), whose sum is σ = 18382848. Its totient is φ = 15649200.

The previous prime is 16978411. The next prime is 16978459. The reversal of 16978421 is 12487961.

It is a cyclic number.

It is not a de Polignac number, because 16978421 - 2²² = 12784117 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

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

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62516 + ... + 62786.

It is an arithmetic number, because the mean of its divisors is an integer number (1148928).

Almost surely, 2^16978421 is an apocalyptic number.

It is an amenable number.

16978421 is a deficient number, since it is larger than the sum of its proper divisors (1404427).

16978421 is a wasteful number, since it uses less digits than its factorization.

16978421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 392.

The product of its digits is 24192, while the sum is 38.

The square root of 16978421 is about 4120.4879565411. The cubic root of 16978421 is about 257.0193175384.

The spelling of 16978421 in words is "sixteen million, nine hundred seventy-eight thousand, four hundred twenty-one".