21738934565431 has 2 divisors, whose sum is σ = 21738934565432. Its totient is φ = 21738934565430.

The previous prime is 21738934565423. The next prime is 21738934565437. The reversal of 21738934565431 is 13456543983712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21738934565431 - 2³ = 21738934565423 is a prime.

It is a super-2 number, since 2×21738934565431² (a number of 27 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 21738934565431.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21738934565437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10869467282715 + 10869467282716.

It is an arithmetic number, because the mean of its divisors is an integer number (10869467282716).

Almost surely, 2^{21738934565431} is an apocalyptic number.

21738934565431 is a deficient number, since it is larger than the sum of its proper divisors (1).

21738934565431 is an equidigital number, since it uses as much as digits as its factorization.

21738934565431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 65318400, while the sum is 61.

The spelling of 21738934565431 in words is "twenty-one trillion, seven hundred thirty-eight billion, nine hundred thirty-four million, five hundred sixty-five thousand, four hundred thirty-one".