21351688 has 16 divisors (see below), whose sum is σ = 40599360. Its totient is φ = 10525200.

The previous prime is 21351679. The next prime is 21351709. The reversal of 21351688 is 88615312.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18228 + ... + 19363.

It is an arithmetic number, because the mean of its divisors is an integer number (2537460).

Almost surely, 2^21351688 is an apocalyptic number.

It is an amenable number.

21351688 is a deficient number, since it is larger than the sum of its proper divisors (19247672).

21351688 is a wasteful number, since it uses less digits than its factorization.

21351688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37668 (or 37664 counting only the distinct ones).

The product of its digits is 11520, while the sum is 34.

The square root of 21351688 is about 4620.7886772714. The cubic root of 21351688 is about 277.4240270339.

The spelling of 21351688 in words is "twenty-one million, three hundred fifty-one thousand, six hundred eighty-eight".