640932974861 has 2 divisors, whose sum is σ = 640932974862. Its totient is φ = 640932974860.

The previous prime is 640932974837. The next prime is 640932974881. The reversal of 640932974861 is 168479239046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 486114333961 + 154818640900 = 697219^2 + 393470^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640932974861 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640932974861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640932974881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320466487430 + 320466487431.

It is an arithmetic number, because the mean of its divisors is an integer number (320466487431).

Almost surely, 2^640932974861 is an apocalyptic number.

It is an amenable number.

640932974861 is a deficient number, since it is larger than the sum of its proper divisors (1).

640932974861 is an equidigital number, since it uses as much as digits as its factorization.

640932974861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15676416, while the sum is 59.

The spelling of 640932974861 in words is "six hundred forty billion, nine hundred thirty-two million, nine hundred seventy-four thousand, eight hundred sixty-one".