668735691 has 32 divisors (see below), whose sum is σ = 974164800. Its totient is φ = 405609984.

The previous prime is 668735687. The next prime is 668735713. The reversal of 668735691 is 196537866.

It is not a de Polignac number, because 668735691 - 2² = 668735687 is a prime.

It is not an unprimeable number, because it can be changed into a prime (668735611) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 911961 + ... + 912693.

It is an arithmetic number, because the mean of its divisors is an integer number (30442650).

Almost surely, 2^668735691 is an apocalyptic number.

668735691 is a deficient number, since it is larger than the sum of its proper divisors (305429109).

668735691 is a wasteful number, since it uses less digits than its factorization.

668735691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1055.

The product of its digits is 1632960, while the sum is 51.

The square root of 668735691 is about 25859.9244198431. The cubic root of 668735691 is about 874.4832610450.

The spelling of 668735691 in words is "six hundred sixty-eight million, seven hundred thirty-five thousand, six hundred ninety-one".