21423564 has 36 divisors (see below), whose sum is σ = 57006040. Its totient is φ = 6765120.

The previous prime is 21423559. The next prime is 21423581. The reversal of 21423564 is 46532412.

It is a tau number, because it is divible by the number of its divisors (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14977 + ... + 16344.

Almost surely, 2^21423564 is an apocalyptic number.

It is an amenable number.

21423564 is an abundant number, since it is smaller than the sum of its proper divisors (35582476).

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

21423564 is a wasteful number, since it uses less digits than its factorization.

21423564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31350 (or 31345 counting only the distinct ones).

The product of its digits is 5760, while the sum is 27.

The square root of 21423564 is about 4628.5596031595. The cubic root of 21423564 is about 277.7349750701.

Adding to 21423564 its reverse (46532412), we get a palindrome (67955976).

The spelling of 21423564 in words is "twenty-one million, four hundred twenty-three thousand, five hundred sixty-four".