668736637866 has 48 divisors (see below), whose sum is σ = 1580768542080. Its totient is φ = 202632298560.

The previous prime is 668736637859. The next prime is 668736637901.

668736637866 is a `hidden beast` number, since 66 + 87 + 3 + 66 + 378 + 66 = 666.

668736637866 is nontrivially palindromic in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 668736637794 and 668736637803.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2682975 + ... + 2921613.

It is an arithmetic number, because the mean of its divisors is an integer number (32932677960).

Almost surely, 2^668736637866 is an apocalyptic number.

668736637866 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

668736637866 is an abundant number, since it is smaller than the sum of its proper divisors (912031904214).

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

668736637866 is a wasteful number, since it uses less digits than its factorization.

668736637866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252811 (or 252808 counting only the distinct ones).

The product of its digits is 1316818944, while the sum is 72.

The spelling of 668736637866 in words is "six hundred sixty-eight billion, seven hundred thirty-six million, six hundred thirty-seven thousand, eight hundred sixty-six".