640256666445 has 24 divisors (see below), whose sum is σ = 1210667152032. Its totient is φ = 310427474400.

The previous prime is 640256666419. The next prime is 640256666447. The reversal of 640256666445 is 544666652046.

It is not a de Polignac number, because 640256666445 - 2²² = 640252472141 is a prime.

It is a super-3 number, since 3×640256666445³ (a number of 36 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 640256666391 and 640256666400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640256666447) 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, 646723411 + ... + 646724400.

It is an arithmetic number, because the mean of its divisors is an integer number (50444464668).

Almost surely, 2^640256666445 is an apocalyptic number.

It is an amenable number.

640256666445 is a deficient number, since it is larger than the sum of its proper divisors (570410485587).

640256666445 is a wasteful number, since it uses less digits than its factorization.

640256666445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1293447833 (or 1293447830 counting only the distinct ones).

The product of its (nonzero) digits is 24883200, while the sum is 54.

The spelling of 640256666445 in words is "six hundred forty billion, two hundred fifty-six million, six hundred sixty-six thousand, four hundred forty-five".