21564800 has 96 divisors (see below), whose sum is σ = 55777680. Its totient is φ = 8222720.

The previous prime is 21564793. The next prime is 21564929. The reversal of 21564800 is 846512.

It is a super-3 number, since 3×21564800³ (a number of 23 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21564800.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 73454 + ... + 73746.

Almost surely, 2^21564800 is an apocalyptic number.

21564800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21564800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27888840).

21564800 is an abundant number, since it is smaller than the sum of its proper divisors (34212880).

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

21564800 is a wasteful number, since it uses less digits than its factorization.

21564800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340 (or 323 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 21564800 is about 4643.7915543228. The cubic root of 21564800 is about 278.3439663509.

The spelling of 21564800 in words is "twenty-one million, five hundred sixty-four thousand, eight hundred".