21466978 has 16 divisors (see below), whose sum is σ = 35070840. Its totient is φ = 9795456.

The previous prime is 21466969. The next prime is 21466987. The reversal of 21466978 is 87966412.

It is an interprime number because it is at equal distance from previous prime (21466969) and next prime (21466987).

It can be written as a sum of positive squares in 4 ways, for example, as 15000129 + 6466849 = 3873^2 + 2543^2 .

It is a super-2 number, since 2×21466978² = 921662288904968, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2325 + ... + 6952.

Almost surely, 2^21466978 is an apocalyptic number.

21466978 is a deficient number, since it is larger than the sum of its proper divisors (13603862).

21466978 is a wasteful number, since it uses less digits than its factorization.

21466978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9381.

The product of its digits is 145152, while the sum is 43.

The square root of 21466978 is about 4633.2470255750. The cubic root of 21466978 is about 277.9224547789.

The spelling of 21466978 in words is "twenty-one million, four hundred sixty-six thousand, nine hundred seventy-eight".