21253688 has 32 divisors (see below), whose sum is σ = 41655600. Its totient is φ = 10156032.

The previous prime is 21253667. The next prime is 21253697. The reversal of 21253688 is 88635212.

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, 16856 + ... + 18072.

Almost surely, 2^21253688 is an apocalyptic number.

It is an amenable number.

21253688 is a deficient number, since it is larger than the sum of its proper divisors (20401912).

21253688 is a wasteful number, since it uses less digits than its factorization.

21253688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1319 (or 1315 counting only the distinct ones).

The product of its digits is 23040, while the sum is 35.

The square root of 21253688 is about 4610.1722310560. The cubic root of 21253688 is about 276.9989356439.

The spelling of 21253688 in words is "twenty-one million, two hundred fifty-three thousand, six hundred eighty-eight".