21920686 has 4 divisors (see below), whose sum is σ = 32881032. Its totient is φ = 10960342.

The previous prime is 21920681. The next prime is 21920693. The reversal of 21920686 is 68602912.

It is a happy number.

It is a semiprime because it is the product of two primes.

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 as a sum of consecutive naturals, namely, 5480170 + ... + 5480173.

It is an arithmetic number, because the mean of its divisors is an integer number (8220258).

Almost surely, 2^21920686 is an apocalyptic number.

21920686 is a deficient number, since it is larger than the sum of its proper divisors (10960346).

21920686 is a wasteful number, since it uses less digits than its factorization.

21920686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10960345.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 21920686 is about 4681.9532248838. The cubic root of 21920686 is about 279.8667988887.

The spelling of 21920686 in words is "twenty-one million, nine hundred twenty thousand, six hundred eighty-six".