668791601 has 4 divisors (see below), whose sum is σ = 670242804. Its totient is φ = 667340400.

The previous prime is 668791589. The next prime is 668791603. The reversal of 668791601 is 106197866.

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 341362576 + 327429025 = 18476^2 + 18095^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668791601 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (668791603) 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, 724910 + ... + 725831.

It is an arithmetic number, because the mean of its divisors is an integer number (167560701).

Almost surely, 2^668791601 is an apocalyptic number.

It is an amenable number.

668791601 is a deficient number, since it is larger than the sum of its proper divisors (1451203).

668791601 is a wasteful number, since it uses less digits than its factorization.

668791601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1451202.

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 668791601 is about 25861.0054135565. The cubic root of 668791601 is about 874.5076309105.

The spelling of 668791601 in words is "six hundred sixty-eight million, seven hundred ninety-one thousand, six hundred one".