668878697 has 4 divisors (see below), whose sum is σ = 669269076. Its totient is φ = 668488320.

The previous prime is 668878687. The next prime is 668878739. The reversal of 668878697 is 796878866.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 373416976 + 295461721 = 19324^2 + 17189^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668878697 is a prime.

It is a super-2 number, since 2×668878697² = 894797422600835618, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (668878627) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 192608 + ... + 196049.

It is an arithmetic number, because the mean of its divisors is an integer number (167317269).

Almost surely, 2^668878697 is an apocalyptic number.

It is an amenable number.

668878697 is a deficient number, since it is larger than the sum of its proper divisors (390379).

668878697 is a wasteful number, since it uses less digits than its factorization.

668878697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390378.

The product of its digits is 48771072, while the sum is 65.

The square root of 668878697 is about 25862.6892839859. The cubic root of 668878697 is about 874.5455913207.

The spelling of 668878697 in words is "six hundred sixty-eight million, eight hundred seventy-eight thousand, six hundred ninety-seven".