21920680 has 32 divisors (see below), whose sum is σ = 51919200. Its totient is φ = 8306496.

The previous prime is 21920671. The next prime is 21920681. The reversal of 21920680 is 8602912.

It is a happy 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 7 ways as a sum of consecutive naturals, for example, 13662 + ... + 15181.

It is an arithmetic number, because the mean of its divisors is an integer number (1622475).

Almost surely, 2^21920680 is an apocalyptic number.

21920680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21920680 is an abundant number, since it is smaller than the sum of its proper divisors (29998520).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21920680 is a wasteful number, since it uses less digits than its factorization.

21920680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28873 (or 28869 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 21920680 is about 4681.9525841256. The cubic root of 21920680 is about 279.8667733543.

The spelling of 21920680 in words is "twenty-one million, nine hundred twenty thousand, six hundred eighty".