21165246413 has 2 divisors, whose sum is σ = 21165246414. Its totient is φ = 21165246412.

The previous prime is 21165246371. The next prime is 21165246451. The reversal of 21165246413 is 31464256112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20785853929 + 379392484 = 144173^2 + 19478^2 .

It is a cyclic number.

It is not a de Polignac number, because 21165246413 - 2¹⁰ = 21165245389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21167246413) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10582623206 + 10582623207.

It is an arithmetic number, because the mean of its divisors is an integer number (10582623207).

Almost surely, 2^21165246413 is an apocalyptic number.

It is an amenable number.

21165246413 is a deficient number, since it is larger than the sum of its proper divisors (1).

21165246413 is an equidigital number, since it uses as much as digits as its factorization.

21165246413 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34560, while the sum is 35.

The spelling of 21165246413 in words is "twenty-one billion, one hundred sixty-five million, two hundred forty-six thousand, four hundred thirteen".