668939811 has 8 divisors (see below), whose sum is σ = 892136640. Its totient is φ = 445851432.

The previous prime is 668939809. The next prime is 668939819. The reversal of 668939811 is 118939866.

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

It is not a de Polignac number, because 668939811 - 2¹ = 668939809 is a prime.

It is not an unprimeable number, because it can be changed into a prime (668939819) 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, 11421 + ... + 38318.

It is an arithmetic number, because the mean of its divisors is an integer number (111517080).

Almost surely, 2^668939811 is an apocalyptic number.

668939811 is a deficient number, since it is larger than the sum of its proper divisors (223196829).

668939811 is a wasteful number, since it uses less digits than its factorization.

668939811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54225.

The product of its digits is 559872, while the sum is 51.

The square root of 668939811 is about 25863.8707659932. The cubic root of 668939811 is about 874.5722256227.

Subtracting from 668939811 its reverse (118939866), we obtain a palindrome (549999945).

The spelling of 668939811 in words is "six hundred sixty-eight million, nine hundred thirty-nine thousand, eight hundred eleven".