640811071 has 2 divisors, whose sum is σ = 640811072. Its totient is φ = 640811070.

The previous prime is 640811063. The next prime is 640811111. The reversal of 640811071 is 170118046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640811071 - 2³ = 640811063 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640811011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320405535 + 320405536.

It is an arithmetic number, because the mean of its divisors is an integer number (320405536).

Almost surely, 2^640811071 is an apocalyptic number.

640811071 is a deficient number, since it is larger than the sum of its proper divisors (1).

640811071 is an equidigital number, since it uses as much as digits as its factorization.

640811071 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1344, while the sum is 28.

The square root of 640811071 is about 25314.2464039521. The cubic root of 640811071 is about 862.1377639000.

The spelling of 640811071 in words is "six hundred forty million, eight hundred eleven thousand, seventy-one".