21642688 has 14 divisors (see below), whose sum is σ = 42947336. Its totient is φ = 10821312.

The previous prime is 21642667. The next prime is 21642727. The reversal of 21642688 is 88624612.

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 as a sum of consecutive naturals, namely, 169020 + ... + 169147.

Almost surely, 2^21642688 is an apocalyptic number.

It is an amenable number.

21642688 is a deficient number, since it is larger than the sum of its proper divisors (21304648).

21642688 is an equidigital number, since it uses as much as digits as its factorization.

21642688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338179 (or 338169 counting only the distinct ones).

The product of its digits is 36864, while the sum is 37.

The square root of 21642688 is about 4652.1702462399. The cubic root of 21642688 is about 278.6786723866.

The spelling of 21642688 in words is "twenty-one million, six hundred forty-two thousand, six hundred eighty-eight".