21955660 has 12 divisors (see below), whose sum is σ = 46106928. Its totient is φ = 8782256.

The previous prime is 21955649. The next prime is 21955673. The reversal of 21955660 is 6655912.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 548872 + ... + 548911.

It is an arithmetic number, because the mean of its divisors is an integer number (3842244).

Almost surely, 2^21955660 is an apocalyptic number.

21955660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21955660 is an abundant number, since it is smaller than the sum of its proper divisors (24151268).

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

21955660 is a wasteful number, since it uses less digits than its factorization.

21955660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1097792 (or 1097790 counting only the distinct ones).

The product of its (nonzero) digits is 16200, while the sum is 34.

The square root of 21955660 is about 4685.6867159468. The cubic root of 21955660 is about 280.0155603597.

The spelling of 21955660 in words is "twenty-one million, nine hundred fifty-five thousand, six hundred sixty".