640256622021 has 40 divisors (see below), whose sum is σ = 958500164160. Its totient is φ = 425916168192.

The previous prime is 640256621987. The next prime is 640256622119. The reversal of 640256622021 is 120226652046.

640256622021 is a `hidden beast` number, since 6 + 4 + 0 + 2 + 5 + 6 + 622 + 0 + 21 = 666.

It is not a de Polignac number, because 640256622021 - 2⁶ = 640256621957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640256623021) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 80663365 + ... + 80671301.

It is an arithmetic number, because the mean of its divisors is an integer number (23962504104).

Almost surely, 2^640256622021 is an apocalyptic number.

It is an amenable number.

640256622021 is a deficient number, since it is larger than the sum of its proper divisors (318243542139).

640256622021 is a wasteful number, since it uses less digits than its factorization.

640256622021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9975 (or 9966 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The spelling of 640256622021 in words is "six hundred forty billion, two hundred fifty-six million, six hundred twenty-two thousand, twenty-one".