640643664612 has 96 divisors (see below), whose sum is σ = 1726943475712. Its totient is φ = 181056508416.

The previous prime is 640643664607. The next prime is 640643664629. The reversal of 640643664612 is 216466346046.

It is a super-2 number, since 2×640643664612² (a number of 24 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7597788 + ... + 7681644.

Almost surely, 2^640643664612 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640643664612, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (863471737856).

640643664612 is an abundant number, since it is smaller than the sum of its proper divisors (1086299811100).

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

640643664612 is a wasteful number, since it uses less digits than its factorization.

640643664612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84857 (or 84855 counting only the distinct ones).

The product of its (nonzero) digits is 2985984, while the sum is 48.

The spelling of 640643664612 in words is "six hundred forty billion, six hundred forty-three million, six hundred sixty-four thousand, six hundred twelve".