21731504369 has 2 divisors, whose sum is σ = 21731504370. Its totient is φ = 21731504368.

The previous prime is 21731504359. The next prime is 21731504387. The reversal of 21731504369 is 96340513712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15206095969 + 6525408400 = 123313^2 + 80780^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21731504369 is a prime.

It is a super-2 number, since 2×21731504369² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21731504329) 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, 10865752184 + 10865752185.

It is an arithmetic number, because the mean of its divisors is an integer number (10865752185).

Almost surely, 2^21731504369 is an apocalyptic number.

It is an amenable number.

21731504369 is a deficient number, since it is larger than the sum of its proper divisors (1).

21731504369 is an equidigital number, since it uses as much as digits as its factorization.

21731504369 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 136080, while the sum is 41.

The spelling of 21731504369 in words is "twenty-one billion, seven hundred thirty-one million, five hundred four thousand, three hundred sixty-nine".