640766753 has 12 divisors (see below), whose sum is σ = 715868244. Its totient is φ = 572959200.

The previous prime is 640766741. The next prime is 640766759. The reversal of 640766753 is 357667046.

It can be written as a sum of positive squares in 2 ways, for example, as 200732224 + 440034529 = 14168^2 + 20977^2 .

It is not a de Polignac number, because 640766753 - 2¹⁰ = 640765729 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (640766759) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 36026 + ... + 50787.

It is an arithmetic number, because the mean of its divisors is an integer number (59655687).

Almost surely, 2^640766753 is an apocalyptic number.

It is an amenable number.

640766753 is a deficient number, since it is larger than the sum of its proper divisors (75101491).

640766753 is a wasteful number, since it uses less digits than its factorization.

640766753 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86896 (or 86885 counting only the distinct ones).

The product of its (nonzero) digits is 635040, while the sum is 44.

The square root of 640766753 is about 25313.3710319270. The cubic root of 640766753 is about 862.1178885140.

The spelling of 640766753 in words is "six hundred forty million, seven hundred sixty-six thousand, seven hundred fifty-three".