640766759 has 2 divisors, whose sum is σ = 640766760. Its totient is φ = 640766758.

The previous prime is 640766741. The next prime is 640766813. The reversal of 640766759 is 957667046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640766759 - 2¹² = 640762663 is a prime.

It is a super-4 number, since 4×640766759⁴ (a number of 36 digits) contains 4444 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640763759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320383379 + 320383380.

It is an arithmetic number, because the mean of its divisors is an integer number (320383380).

Almost surely, 2^640766759 is an apocalyptic number.

640766759 is a deficient number, since it is larger than the sum of its proper divisors (1).

640766759 is an equidigital number, since it uses as much as digits as its factorization.

640766759 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1905120, while the sum is 50.

The square root of 640766759 is about 25313.3711504414. The cubic root of 640766759 is about 862.1178912049.

The spelling of 640766759 in words is "six hundred forty million, seven hundred sixty-six thousand, seven hundred fifty-nine".