21242731577 has 2 divisors, whose sum is σ = 21242731578. Its totient is φ = 21242731576.

The previous prime is 21242731487. The next prime is 21242731589. The reversal of 21242731577 is 77513724212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14703745081 + 6538986496 = 121259^2 + 80864^2 .

It is a cyclic number.

It is not a de Polignac number, because 21242731577 - 2²⁸ = 20974296121 is a prime.

It is not a weakly prime, because it can be changed into another prime (21247731577) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621365788 + 10621365789.

It is an arithmetic number, because the mean of its divisors is an integer number (10621365789).

Almost surely, 2^21242731577 is an apocalyptic number.

It is an amenable number.

21242731577 is a deficient number, since it is larger than the sum of its proper divisors (1).

21242731577 is an equidigital number, since it uses as much as digits as its factorization.

21242731577 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 164640, while the sum is 41.

The spelling of 21242731577 in words is "twenty-one billion, two hundred forty-two million, seven hundred thirty-one thousand, five hundred seventy-seven".