640766741 has 2 divisors, whose sum is σ = 640766742. Its totient is φ = 640766740.

The previous prime is 640766713. The next prime is 640766759. The reversal of 640766741 is 147667046.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 600495025 + 40271716 = 24505^2 + 6346^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640766741 is a prime.

It is a super-2 number, since 2×640766741² = 821164032743522162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640766341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320383370 + 320383371.

It is an arithmetic number, because the mean of its divisors is an integer number (320383371).

Almost surely, 2^640766741 is an apocalyptic number.

It is an amenable number.

640766741 is a deficient number, since it is larger than the sum of its proper divisors (1).

640766741 is an equidigital number, since it uses as much as digits as its factorization.

640766741 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 169344, while the sum is 41.

The square root of 640766741 is about 25313.3707948981. The cubic root of 640766741 is about 862.1178831322.

The spelling of 640766741 in words is "six hundred forty million, seven hundred sixty-six thousand, seven hundred forty-one".