640834757 has 2 divisors, whose sum is σ = 640834758. Its totient is φ = 640834756.

The previous prime is 640834739. The next prime is 640834769. The reversal of 640834757 is 757438046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 541911841 + 98922916 = 23279^2 + 9946^2 .

It is a cyclic number.

It is not a de Polignac number, because 640834757 - 2⁶ = 640834693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640834157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320417378 + 320417379.

It is an arithmetic number, because the mean of its divisors is an integer number (320417379).

Almost surely, 2^640834757 is an apocalyptic number.

It is an amenable number.

640834757 is a deficient number, since it is larger than the sum of its proper divisors (1).

640834757 is an equidigital number, since it uses as much as digits as its factorization.

640834757 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 564480, while the sum is 44.

The square root of 640834757 is about 25314.7142389560. The cubic root of 640834757 is about 862.1483860342.

The spelling of 640834757 in words is "six hundred forty million, eight hundred thirty-four thousand, seven hundred fifty-seven".