21947880 has 32 divisors (see below), whose sum is σ = 65844000. Its totient is φ = 5852736.

The previous prime is 21947857. The next prime is 21947897. The reversal of 21947880 is 8874912.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 91330 + ... + 91569.

It is an arithmetic number, because the mean of its divisors is an integer number (2057625).

Almost surely, 2^21947880 is an apocalyptic number.

21947880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21947880 is an abundant number, since it is smaller than the sum of its proper divisors (43896120).

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

21947880 is a wasteful number, since it uses less digits than its factorization.

21947880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182913 (or 182909 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 39.

The square root of 21947880 is about 4684.8564545779. The cubic root of 21947880 is about 279.9824818972.

The spelling of 21947880 in words is "twenty-one million, nine hundred forty-seven thousand, eight hundred eighty".