668665566802 has 16 divisors (see below), whose sum is σ = 1065627327960. Its totient is φ = 314079631488.

The previous prime is 668665566787. The next prime is 668665566841. The reversal of 668665566802 is 208665566866.

It can be written as a sum of positive squares in 4 ways, for example, as 647527605481 + 21137961321 = 804691^2 + 145389^2 .

It is a super-2 number, since 2×668665566802² (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 7 ways as a sum of consecutive naturals, for example, 155791323 + ... + 155795614.

Almost surely, 2^668665566802 is an apocalyptic number.

668665566802 is a deficient number, since it is larger than the sum of its proper divisors (396961761158).

668665566802 is a wasteful number, since it uses less digits than its factorization.

668665566802 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 311587005.

The product of its (nonzero) digits is 149299200, while the sum is 64.

Adding to 668665566802 its sum of digits (64), we get a palindrome (668665566866).

The spelling of 668665566802 in words is "six hundred sixty-eight billion, six hundred sixty-five million, five hundred sixty-six thousand, eight hundred two".