21756372313397 has 2 divisors, whose sum is σ = 21756372313398. Its totient is φ = 21756372313396.

The previous prime is 21756372313327. The next prime is 21756372313421. The reversal of 21756372313397 is 79331327365712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21749528722321 + 6843591076 = 4663639^2 + 82726^2 .

It is a cyclic number.

It is not a de Polignac number, because 21756372313397 - 2³⁸ = 21481494406453 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21756372313327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10878186156698 + 10878186156699.

It is an arithmetic number, because the mean of its divisors is an integer number (10878186156699).

Almost surely, 2^{21756372313397} is an apocalyptic number.

It is an amenable number.

21756372313397 is a deficient number, since it is larger than the sum of its proper divisors (1).

21756372313397 is an equidigital number, since it uses as much as digits as its factorization.

21756372313397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30005640, while the sum is 59.

The spelling of 21756372313397 in words is "twenty-one trillion, seven hundred fifty-six billion, three hundred seventy-two million, three hundred thirteen thousand, three hundred ninety-seven".