21955880 has 16 divisors (see below), whose sum is σ = 49400820. Its totient is φ = 8782336.

The previous prime is 21955877. The next prime is 21955889. The reversal of 21955880 is 8855912.

It can be written as a sum of positive squares in 2 ways, for example, as 19945156 + 2010724 = 4466^2 + 1418^2 .

It is not an unprimeable number, because it can be changed into a prime (21955889) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 274409 + ... + 274488.

Almost surely, 2^21955880 is an apocalyptic number.

21955880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21955880 is an abundant number, since it is smaller than the sum of its proper divisors (27444940).

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

21955880 is a wasteful number, since it uses less digits than its factorization.

21955880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 548908 (or 548904 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 38.

The square root of 21955880 is about 4685.7101916358. The cubic root of 21955880 is about 280.0164956268.

The spelling of 21955880 in words is "twenty-one million, nine hundred fifty-five thousand, eight hundred eighty".