21856280 has 32 divisors (see below), whose sum is σ = 50379840. Its totient is φ = 8528640.

The previous prime is 21856277. The next prime is 21856337. The reversal of 21856280 is 8265812.

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors.

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, 5024 + ... + 8303.

It is an arithmetic number, because the mean of its divisors is an integer number (1574370).

Almost surely, 2^21856280 is an apocalyptic number.

21856280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21856280 is an abundant number, since it is smaller than the sum of its proper divisors (28523560).

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

21856280 is a wasteful number, since it uses less digits than its factorization.

21856280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13379 (or 13375 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 32.

The square root of 21856280 is about 4675.0700529511. The cubic root of 21856280 is about 279.5924342493.

The spelling of 21856280 in words is "twenty-one million, eight hundred fifty-six thousand, two hundred eighty".