21572563 has 2 divisors, whose sum is σ = 21572564. Its totient is φ = 21572562.

The previous prime is 21572557. The next prime is 21572567. The reversal of 21572563 is 36527512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21572563 - 2⁵ = 21572531 is a prime.

It is not a weakly prime, because it can be changed into another prime (21572567) by changing a digit.

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 as a sum of consecutive naturals, namely, 10786281 + 10786282.

It is an arithmetic number, because the mean of its divisors is an integer number (10786282).

Almost surely, 2^21572563 is an apocalyptic number.

21572563 is a deficient number, since it is larger than the sum of its proper divisors (1).

21572563 is an equidigital number, since it uses as much as digits as its factorization.

21572563 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12600, while the sum is 31.

The square root of 21572563 is about 4644.6273262771. The cubic root of 21572563 is about 278.3773622086.

The spelling of 21572563 in words is "twenty-one million, five hundred seventy-two thousand, five hundred sixty-three".