21232057681 has 2 divisors, whose sum is σ = 21232057682. Its totient is φ = 21232057680.

The previous prime is 21232057667. The next prime is 21232057703. The reversal of 21232057681 is 18675023212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20955168081 + 276889600 = 144759^2 + 16640^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21232057681 is a prime.

It is a super-2 number, since 2×21232057681² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21232057681.

It is not a weakly prime, because it can be changed into another prime (21232057601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10616028840 + 10616028841.

It is an arithmetic number, because the mean of its divisors is an integer number (10616028841).

Almost surely, 2^21232057681 is an apocalyptic number.

It is an amenable number.

21232057681 is a deficient number, since it is larger than the sum of its proper divisors (1).

21232057681 is an equidigital number, since it uses as much as digits as its factorization.

21232057681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40320, while the sum is 37.

The spelling of 21232057681 in words is "twenty-one billion, two hundred thirty-two million, fifty-seven thousand, six hundred eighty-one".