640426868208 has 30 divisors (see below), whose sum is σ = 1792305749624. Its totient is φ = 213475622688.

The previous prime is 640426868203. The next prime is 640426868209. The reversal of 640426868208 is 802868624046.

640426868208 is a `hidden beast` number, since 6 + 4 + 0 + 426 + 8 + 6 + 8 + 208 = 666.

It is a super-2 number, since 2×640426868208² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640426868203) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2223704260 + ... + 2223704547.

Almost surely, 2^640426868208 is an apocalyptic number.

It is an amenable number.

640426868208 is an abundant number, since it is smaller than the sum of its proper divisors (1151878881416).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640426868208 is a wasteful number, since it uses less digits than its factorization.

640426868208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4447408821 (or 4447408812 counting only the distinct ones).

The product of its (nonzero) digits is 7077888, while the sum is 54.

The spelling of 640426868208 in words is "six hundred forty billion, four hundred twenty-six million, eight hundred sixty-eight thousand, two hundred eight".