640006757 has 4 divisors (see below), whose sum is σ = 689238060. Its totient is φ = 590775456.

The previous prime is 640006651. The next prime is 640006777. The reversal of 640006757 is 757600046.

640006757 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 205951201 + 434055556 = 14351^2 + 20834^2 .

It is a cyclic number.

It is not a de Polignac number, because 640006757 - 2¹⁶ = 639941221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640006777) 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, 24615632 + ... + 24615657.

It is an arithmetic number, because the mean of its divisors is an integer number (172309515).

Almost surely, 2^640006757 is an apocalyptic number.

It is an amenable number.

640006757 is a deficient number, since it is larger than the sum of its proper divisors (49231303).

640006757 is a wasteful number, since it uses less digits than its factorization.

640006757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49231302.

The product of its (nonzero) digits is 35280, while the sum is 35.

The square root of 640006757 is about 25298.3548279330. The cubic root of 640006757 is about 861.7769088177.

The spelling of 640006757 in words is "six hundred forty million, six thousand, seven hundred fifty-seven".