21945732961 has 2 divisors, whose sum is σ = 21945732962. Its totient is φ = 21945732960.

The previous prime is 21945732953. The next prime is 21945732971. The reversal of 21945732961 is 16923754912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15936537600 + 6009195361 = 126240^2 + 77519^2 .

It is a cyclic number.

It is not a de Polignac number, because 21945732961 - 2³ = 21945732953 is a prime.

It is not a weakly prime, because it can be changed into another prime (21945732971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10972866480 + 10972866481.

It is an arithmetic number, because the mean of its divisors is an integer number (10972866481).

Almost surely, 2^21945732961 is an apocalyptic number.

It is an amenable number.

21945732961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21945732961 is an equidigital number, since it uses as much as digits as its factorization.

21945732961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 816480, while the sum is 49.

The spelling of 21945732961 in words is "twenty-one billion, nine hundred forty-five million, seven hundred thirty-two thousand, nine hundred sixty-one".