640757049 has 4 divisors (see below), whose sum is σ = 854342736. Its totient is φ = 427171364.

The previous prime is 640756999. The next prime is 640757077. The reversal of 640757049 is 940757046.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 640757049 - 2²¹ = 638659897 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640757049.

It is not an unprimeable number, because it can be changed into a prime (640757099) 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, 106792839 + ... + 106792844.

It is an arithmetic number, because the mean of its divisors is an integer number (213585684).

Almost surely, 2^640757049 is an apocalyptic number.

It is an amenable number.

640757049 is a deficient number, since it is larger than the sum of its proper divisors (213585687).

640757049 is a wasteful number, since it uses less digits than its factorization.

640757049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213585686.

The product of its (nonzero) digits is 211680, while the sum is 42.

The square root of 640757049 is about 25313.1793538465. The cubic root of 640757049 is about 862.1135364185.

The spelling of 640757049 in words is "six hundred forty million, seven hundred fifty-seven thousand, forty-nine".