21757611397 has 2 divisors, whose sum is σ = 21757611398. Its totient is φ = 21757611396.

The previous prime is 21757611391. The next prime is 21757611443. The reversal of 21757611397 is 79311675712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17892005121 + 3865606276 = 133761^2 + 62174^2 .

It is a cyclic number.

It is not a de Polignac number, because 21757611397 - 2³ = 21757611389 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21757611397.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21757611391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10878805698 + 10878805699.

It is an arithmetic number, because the mean of its divisors is an integer number (10878805699).

Almost surely, 2^21757611397 is an apocalyptic number.

It is an amenable number.

21757611397 is a deficient number, since it is larger than the sum of its proper divisors (1).

21757611397 is an equidigital number, since it uses as much as digits as its factorization.

21757611397 is an evil number, because the sum of its binary digits is even.

The product of its digits is 555660, while the sum is 49.

The spelling of 21757611397 in words is "twenty-one billion, seven hundred fifty-seven million, six hundred eleven thousand, three hundred ninety-seven".