665646646566 has 64 divisors (see below), whose sum is σ = 1456007095296. Its totient is φ = 201199680000.

The previous prime is 665646646507. The next prime is 665646646571.

665646646566 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×665646646566² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (66).

It is a junction number, because it is equal to n+sod(n) for n = 665646646497 and 665646646506.

It is a congruent number.

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, 43461726 + ... + 43477038.

It is an arithmetic number, because the mean of its divisors is an integer number (22750110864).

Almost surely, 2^665646646566 is an apocalyptic number.

665646646566 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

665646646566 is an abundant number, since it is smaller than the sum of its proper divisors (790360448730).

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

665646646566 is a wasteful number, since it uses less digits than its factorization.

665646646566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16957.

The product of its digits is 671846400, while the sum is 66.

The spelling of 665646646566 in words is "six hundred sixty-five billion, six hundred forty-six million, six hundred forty-six thousand, five hundred sixty-six".