21390657313 has 2 divisors, whose sum is σ = 21390657314. Its totient is φ = 21390657312.

The previous prime is 21390657307. The next prime is 21390657331. The reversal of 21390657313 is 31375609312.

Together with next prime (21390657331) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16525873809 + 4864783504 = 128553^2 + 69748^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21390657313 is a prime.

It is not a weakly prime, because it can be changed into another prime (21390657383) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10695328656 + 10695328657.

It is an arithmetic number, because the mean of its divisors is an integer number (10695328657).

Almost surely, 2^21390657313 is an apocalyptic number.

It is an amenable number.

21390657313 is a deficient number, since it is larger than the sum of its proper divisors (1).

21390657313 is an equidigital number, since it uses as much as digits as its factorization.

21390657313 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 102060, while the sum is 40.

The spelling of 21390657313 in words is "twenty-one billion, three hundred ninety million, six hundred fifty-seven thousand, three hundred thirteen".