640756606249 has 4 divisors (see below), whose sum is σ = 643506634836. Its totient is φ = 638006577664.

The previous prime is 640756606247. The next prime is 640756606267. The reversal of 640756606249 is 942606657046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 125709248025 + 515047358224 = 354555^2 + 717668^2 .

It is a cyclic number.

It is not a de Polignac number, because 640756606249 - 2¹ = 640756606247 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640756606249.

It is not an unprimeable number, because it can be changed into a prime (640756606247) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1375013944 + ... + 1375014409.

It is an arithmetic number, because the mean of its divisors is an integer number (160876658709).

Almost surely, 2^640756606249 is an apocalyptic number.

It is an amenable number.

640756606249 is a deficient number, since it is larger than the sum of its proper divisors (2750028587).

640756606249 is a wasteful number, since it uses less digits than its factorization.

640756606249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2750028586.

The product of its (nonzero) digits is 13063680, while the sum is 55.

The spelling of 640756606249 in words is "six hundred forty billion, seven hundred fifty-six million, six hundred six thousand, two hundred forty-nine".