640645129 has 2 divisors, whose sum is σ = 640645130. Its totient is φ = 640645128.

The previous prime is 640645111. The next prime is 640645139. The reversal of 640645129 is 921546046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 636401529 + 4243600 = 25227^2 + 2060^2 .

It is a cyclic number.

It is not a de Polignac number, because 640645129 - 2⁷ = 640645001 is a prime.

It is a super-2 number, since 2×640645129² = 820852362622853282, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (640645139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320322564 + 320322565.

It is an arithmetic number, because the mean of its divisors is an integer number (320322565).

Almost surely, 2^640645129 is an apocalyptic number.

It is an amenable number.

640645129 is a deficient number, since it is larger than the sum of its proper divisors (1).

640645129 is an equidigital number, since it uses as much as digits as its factorization.

640645129 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 640645129 is about 25310.9685512033. The cubic root of 640645129 is about 862.0633388356.

The spelling of 640645129 in words is "six hundred forty million, six hundred forty-five thousand, one hundred twenty-nine".