21522961 has 2 divisors, whose sum is σ = 21522962. Its totient is φ = 21522960.

The previous prime is 21522947. The next prime is 21522971. The reversal of 21522961 is 16922512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11943936 + 9579025 = 3456^2 + 3095^2 .

It is a cyclic number.

It is not a de Polignac number, because 21522961 - 2¹³ = 21514769 is a prime.

It is not a weakly prime, because it can be changed into another prime (21522911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10761480 + 10761481.

It is an arithmetic number, because the mean of its divisors is an integer number (10761481).

Almost surely, 2^21522961 is an apocalyptic number.

It is an amenable number.

21522961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21522961 is an equidigital number, since it uses as much as digits as its factorization.

21522961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2160, while the sum is 28.

The square root of 21522961 is about 4639.2845353567. The cubic root of 21522961 is about 278.1638398984.

The spelling of 21522961 in words is "twenty-one million, five hundred twenty-two thousand, nine hundred sixty-one".