21538882 has 16 divisors (see below), whose sum is σ = 33073272. Its totient is φ = 10516480.

The previous prime is 21538873. The next prime is 21538883. The reversal of 21538882 is 28883512.

It is a Cunningham number, because it is equal to 4641²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 19439281 + 2099601 = 4409^2 + 1449^2 .

It is not an unprimeable number, because it can be changed into a prime (21538883) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33282 + ... + 33922.

Almost surely, 2^21538882 is an apocalyptic number.

21538882 is a deficient number, since it is larger than the sum of its proper divisors (11534390).

21538882 is a wasteful number, since it uses less digits than its factorization.

21538882 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1013.

The product of its digits is 30720, while the sum is 37.

The square root of 21538882 is about 4641.0001077354. Note that the first 3 decimals coincide. The cubic root of 21538882 is about 278.2324109305.

The spelling of 21538882 in words is "twenty-one million, five hundred thirty-eight thousand, eight hundred eighty-two".