21880720 has 40 divisors (see below), whose sum is σ = 51068160. Its totient is φ = 8718720.

The previous prime is 21880697. The next prime is 21880753. The reversal of 21880720 is 2708812.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

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, 38035 + ... + 38605.

It is an arithmetic number, because the mean of its divisors is an integer number (1276704).

Almost surely, 2^21880720 is an apocalyptic number.

21880720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21880720 is an abundant number, since it is smaller than the sum of its proper divisors (29187440).

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

21880720 is a wasteful number, since it uses less digits than its factorization.

21880720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1063 (or 1057 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 28.

The square root of 21880720 is about 4677.6831872199. The cubic root of 21880720 is about 279.6966101607.

The spelling of 21880720 in words is "twenty-one million, eight hundred eighty thousand, seven hundred twenty".