21920685 has 16 divisors (see below), whose sum is σ = 35332416. Its totient is φ = 11604608.

The previous prime is 21920681. The next prime is 21920693. The reversal of 21920685 is 58602912.

It is a cyclic number.

It is not a de Polignac number, because 21920685 - 2² = 21920681 is a prime.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 3279 + ... + 7388.

It is an arithmetic number, because the mean of its divisors is an integer number (2208276).

Almost surely, 2^21920685 is an apocalyptic number.

It is an amenable number.

21920685 is a deficient number, since it is larger than the sum of its proper divisors (13411731).

21920685 is a wasteful number, since it uses less digits than its factorization.

21920685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10812.

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21920685 is about 4681.9531180908. The cubic root of 21920685 is about 279.8667946330.

The spelling of 21920685 in words is "twenty-one million, nine hundred twenty thousand, six hundred eighty-five".