21117538 has 8 divisors (see below), whose sum is σ = 34112988. Its totient is φ = 9746544.

The previous prime is 21117521. The next prime is 21117557. The reversal of 21117538 is 83571112.

It can be written as a sum of positive squares in 2 ways, for example, as 20912329 + 205209 = 4573^2 + 453^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21117538² = 891900822362888, which contains 22 as substring.

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, 406081 + ... + 406132.

Almost surely, 2^21117538 is an apocalyptic number.

21117538 is a deficient number, since it is larger than the sum of its proper divisors (12995450).

21117538 is a wasteful number, since it uses less digits than its factorization.

21117538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 812228.

The product of its digits is 1680, while the sum is 28.

The square root of 21117538 is about 4595.3822474306. The cubic root of 21117538 is about 276.4061879611.

The spelling of 21117538 in words is "twenty-one million, one hundred seventeen thousand, five hundred thirty-eight".