668936861 has 4 divisors (see below), whose sum is σ = 671736000. Its totient is φ = 666137724.

The previous prime is 668936839. The next prime is 668936897. The reversal of 668936861 is 168639866.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 668936861 - 2¹⁸ = 668674717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668936461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1399211 + ... + 1399688.

It is an arithmetic number, because the mean of its divisors is an integer number (167934000).

Almost surely, 2^668936861 is an apocalyptic number.

It is an amenable number.

668936861 is a deficient number, since it is larger than the sum of its proper divisors (2799139).

668936861 is a wasteful number, since it uses less digits than its factorization.

668936861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2799138.

The product of its digits is 2239488, while the sum is 53.

The square root of 668936861 is about 25863.8137365703. The cubic root of 668936861 is about 874.5709400103.

The spelling of 668936861 in words is "six hundred sixty-eight million, nine hundred thirty-six thousand, eight hundred sixty-one".