21564280 has 16 divisors (see below), whose sum is σ = 48519720. Its totient is φ = 8625696.

The previous prime is 21564247. The next prime is 21564289. The reversal of 21564280 is 8246512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21564289) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 269514 + ... + 269593.

Almost surely, 2^21564280 is an apocalyptic number.

21564280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21564280 is an abundant number, since it is smaller than the sum of its proper divisors (26955440).

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

21564280 is a wasteful number, since it uses less digits than its factorization.

21564280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 539118 (or 539114 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 28.

The square root of 21564280 is about 4643.7355652535. The cubic root of 21564280 is about 278.3417290626.

The spelling of 21564280 in words is "twenty-one million, five hundred sixty-four thousand, two hundred eighty".