640634413 has 2 divisors, whose sum is σ = 640634414. Its totient is φ = 640634412.

The previous prime is 640634363. The next prime is 640634417. The reversal of 640634413 is 314436046.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 466473604 + 174160809 = 21598^2 + 13197^2 .

It is a cyclic number.

It is not a de Polignac number, because 640634413 - 2⁹ = 640633901 is a prime.

It is a super-2 number, since 2×640634413² = 820824902239709138, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640634417) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320317206 + 320317207.

It is an arithmetic number, because the mean of its divisors is an integer number (320317207).

Almost surely, 2^640634413 is an apocalyptic number.

It is an amenable number.

640634413 is a deficient number, since it is larger than the sum of its proper divisors (1).

640634413 is an equidigital number, since it uses as much as digits as its factorization.

640634413 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 31.

The square root of 640634413 is about 25310.7568634365. The cubic root of 640634413 is about 862.0585322628.

The spelling of 640634413 in words is "six hundred forty million, six hundred thirty-four thousand, four hundred thirteen".