21563264 has 16 divisors (see below), whose sum is σ = 42958320. Its totient is φ = 10781568.

The previous prime is 21563257. The next prime is 21563273. The reversal of 21563264 is 46236512.

It is a tau number, because it is divible by the number of its divisors (16).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84104 + ... + 84359.

It is an arithmetic number, because the mean of its divisors is an integer number (2684895).

Almost surely, 2^21563264 is an apocalyptic number.

It is an amenable number.

21563264 is a deficient number, since it is larger than the sum of its proper divisors (21395056).

21563264 is an equidigital number, since it uses as much as digits as its factorization.

21563264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168477 (or 168465 counting only the distinct ones).

The product of its digits is 8640, while the sum is 29.

The square root of 21563264 is about 4643.6261692776. The cubic root of 21563264 is about 278.3373576416.

Adding to 21563264 its reverse (46236512), we get a palindrome (67799776).

The spelling of 21563264 in words is "twenty-one million, five hundred sixty-three thousand, two hundred sixty-four".