640557209601 has 24 divisors (see below), whose sum is σ = 925995029960. Its totient is φ = 426694127616.

The previous prime is 640557209587. The next prime is 640557209651. The reversal of 640557209601 is 106902755046.

640557209601 is a `hidden beast` number, since 6 + 4 + 0 + 557 + 2 + 0 + 96 + 0 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 266317923600 + 374239286001 = 516060^2 + 611751^2 .

It is not a de Polignac number, because 640557209601 - 2¹¹ = 640557207553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640557209651) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 78026985 + ... + 78035193.

Almost surely, 2^640557209601 is an apocalyptic number.

It is an amenable number.

640557209601 is a deficient number, since it is larger than the sum of its proper divisors (285437820359).

640557209601 is a wasteful number, since it uses less digits than its factorization.

640557209601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14145 (or 14142 counting only the distinct ones).

The product of its (nonzero) digits is 453600, while the sum is 45.

The spelling of 640557209601 in words is "six hundred forty billion, five hundred fifty-seven million, two hundred nine thousand, six hundred one".