668635491 has 8 divisors (see below), whose sum is σ = 891633744. Its totient is φ = 445697120.

The previous prime is 668635477. The next prime is 668635493. The reversal of 668635491 is 194536866.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 668635491 - 2⁵ = 668635459 is a prime.

It is a super-2 number, since 2×668635491² = 894146839649622162, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 668635491.

It is not an unprimeable number, because it can be changed into a prime (668635493) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33601 + ... + 49661.

It is an arithmetic number, because the mean of its divisors is an integer number (111454218).

Almost surely, 2^668635491 is an apocalyptic number.

668635491 is a deficient number, since it is larger than the sum of its proper divisors (222998253).

668635491 is a wasteful number, since it uses less digits than its factorization.

668635491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29941.

The product of its digits is 933120, while the sum is 48.

The square root of 668635491 is about 25857.9869866160. The cubic root of 668635491 is about 874.4395828023.

The spelling of 668635491 in words is "six hundred sixty-eight million, six hundred thirty-five thousand, four hundred ninety-one".