21920684 has 24 divisors (see below), whose sum is σ = 40778640. Its totient is φ = 10274816.

The previous prime is 21920681. The next prime is 21920693. The reversal of 21920684 is 48602912.

It is a self number, because there is not a number n which added to its sum of digits gives 21920684.

It is not an unprimeable number, because it can be changed into a prime (21920681) 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, 23132 + ... + 24060.

It is an arithmetic number, because the mean of its divisors is an integer number (1699110).

Almost surely, 2^21920684 is an apocalyptic number.

It is an amenable number.

21920684 is a deficient number, since it is larger than the sum of its proper divisors (18857956).

21920684 is a wasteful number, since it uses less digits than its factorization.

21920684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1297 (or 1295 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 21920684 is about 4681.9530112977. The cubic root of 21920684 is about 279.8667903772.

The spelling of 21920684 in words is "twenty-one million, nine hundred twenty thousand, six hundred eighty-four".