21389288 has 32 divisors (see below), whose sum is σ = 42636000. Its totient is φ = 10031040.

The previous prime is 21389261. The next prime is 21389317. The reversal of 21389288 is 88298312.

It is a happy number.

It is a super-2 number, since 2×21389288² = 915003282293888, which contains 22 as substring.

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, 15923 + ... + 17213.

It is an arithmetic number, because the mean of its divisors is an integer number (1332375).

Almost surely, 2^21389288 is an apocalyptic number.

It is an amenable number.

21389288 is a deficient number, since it is larger than the sum of its proper divisors (21246712).

21389288 is a wasteful number, since it uses less digits than its factorization.

21389288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1425 (or 1421 counting only the distinct ones).

The product of its digits is 55296, while the sum is 41.

The square root of 21389288 is about 4624.8554572008. The cubic root of 21389288 is about 277.5867780441.

The spelling of 21389288 in words is "twenty-one million, three hundred eighty-nine thousand, two hundred eighty-eight".