21640662413 has 2 divisors, whose sum is σ = 21640662414. Its totient is φ = 21640662412.

The previous prime is 21640662409. The next prime is 21640662419. The reversal of 21640662413 is 31426604612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13868124169 + 7772538244 = 117763^2 + 88162^2 .

It is a cyclic number.

It is not a de Polignac number, because 21640662413 - 2² = 21640662409 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21640662419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10820331206 + 10820331207.

It is an arithmetic number, because the mean of its divisors is an integer number (10820331207).

Almost surely, 2^21640662413 is an apocalyptic number.

It is an amenable number.

21640662413 is a deficient number, since it is larger than the sum of its proper divisors (1).

21640662413 is an equidigital number, since it uses as much as digits as its factorization.

21640662413 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 41472, while the sum is 35.

The spelling of 21640662413 in words is "twenty-one billion, six hundred forty million, six hundred sixty-two thousand, four hundred thirteen".