21678748 has 24 divisors (see below), whose sum is σ = 46693472. Its totient is φ = 8576064.

The previous prime is 21678733. The next prime is 21678763. The reversal of 21678748 is 84787612.

It is an interprime number because it is at equal distance from previous prime (21678733) and next prime (21678763).

It is a super-2 number, since 2×21678748² = 939936229695008, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29415 + ... + 30142.

Almost surely, 2^21678748 is an apocalyptic number.

21678748 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21678748 is an abundant number, since it is smaller than the sum of its proper divisors (25014724).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21678748 is a wasteful number, since it uses less digits than its factorization.

21678748 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59581 (or 59579 counting only the distinct ones).

The product of its digits is 150528, while the sum is 43.

The square root of 21678748 is about 4656.0442437760. The cubic root of 21678748 is about 278.8333601491.

The spelling of 21678748 in words is "twenty-one million, six hundred seventy-eight thousand, seven hundred forty-eight".