21555982 has 12 divisors (see below), whose sum is σ = 37613160. Its totient is φ = 9238236.

The previous prime is 21555967. The next prime is 21556009. The reversal of 21555982 is 28955512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 109882 + ... + 110077.

It is an arithmetic number, because the mean of its divisors is an integer number (3134430).

Almost surely, 2^21555982 is an apocalyptic number.

21555982 is a deficient number, since it is larger than the sum of its proper divisors (16057178).

21555982 is a wasteful number, since it uses less digits than its factorization.

21555982 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219975 (or 219968 counting only the distinct ones).

The product of its digits is 36000, while the sum is 37.

The square root of 21555982 is about 4642.8420175578. The cubic root of 21555982 is about 278.3060222365.

The spelling of 21555982 in words is "twenty-one million, five hundred fifty-five thousand, nine hundred eighty-two".