646665704064 has 256 divisors, whose sum is σ = 2011808016000. Its totient is φ = 203926118400.

The previous prime is 646665704059. The next prime is 646665704089. The reversal of 646665704064 is 460407566646.

It is a happy number.

It is a super-2 number, since 2×646665704064² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 646665704064.

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, 49963834 + ... + 49976774.

Almost surely, 2^646665704064 is an apocalyptic number.

646665704064 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646665704064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1005904008000).

646665704064 is an abundant number, since it is smaller than the sum of its proper divisors (1365142311936).

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

646665704064 is a wasteful number, since it uses less digits than its factorization.

646665704064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13744 (or 13726 counting only the distinct ones).

The product of its (nonzero) digits is 17418240, while the sum is 54.

The spelling of 646665704064 in words is "six hundred forty-six billion, six hundred sixty-five million, seven hundred four thousand, sixty-four".