640661051 has 2 divisors, whose sum is σ = 640661052. Its totient is φ = 640661050.

The previous prime is 640661033. The next prime is 640661053. The reversal of 640661051 is 150166046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640661051 - 2¹⁸ = 640398907 is a prime.

It is a Sophie Germain prime.

Together with 640661053, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (640661053) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320330525 + 320330526.

It is an arithmetic number, because the mean of its divisors is an integer number (320330526).

Almost surely, 2^640661051 is an apocalyptic number.

640661051 is a deficient number, since it is larger than the sum of its proper divisors (1).

640661051 is an equidigital number, since it uses as much as digits as its factorization.

640661051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 640661051 is about 25311.2830769205. The cubic root of 640661051 is about 862.0704804174.

The spelling of 640661051 in words is "six hundred forty million, six hundred sixty-one thousand, fifty-one".