21678868 has 12 divisors (see below), whose sum is σ = 37972480. Its totient is φ = 10829592.

The previous prime is 21678823. The next prime is 21678907. The reversal of 21678868 is 86887612.

It is a super-2 number, since 2×21678868² = 939946635522848, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 5023 + ... + 8281.

Almost surely, 2^21678868 is an apocalyptic number.

It is an amenable number.

21678868 is a deficient number, since it is larger than the sum of its proper divisors (16293612).

21678868 is a wasteful number, since it uses less digits than its factorization.

21678868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4926 (or 4924 counting only the distinct ones).

The product of its digits is 258048, while the sum is 46.

The square root of 21678868 is about 4656.0571302337. The cubic root of 21678868 is about 278.8338746306.

The spelling of 21678868 in words is "twenty-one million, six hundred seventy-eight thousand, eight hundred sixty-eight".