21552720 has 80 divisors (see below), whose sum is σ = 76364160. Its totient is φ = 4925952.

The previous prime is 21552709. The next prime is 21552731. The reversal of 21552720 is 2725512.

It is an interprime number because it is at equal distance from previous prime (21552709) and next prime (21552731).

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4735 + ... + 8094.

It is an arithmetic number, because the mean of its divisors is an integer number (954552).

Almost surely, 2^21552720 is an apocalyptic number.

21552720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21552720 is an abundant number, since it is smaller than the sum of its proper divisors (54811440).

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

21552720 is a wasteful number, since it uses less digits than its factorization.

21552720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12852 (or 12846 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 21552720 is about 4642.4907108146. The cubic root of 21552720 is about 278.2919831321.

The spelling of 21552720 in words is "twenty-one million, five hundred fifty-two thousand, seven hundred twenty".