668617918 has 4 divisors (see below), whose sum is σ = 1002926880. Its totient is φ = 334308958.

The previous prime is 668617907. The next prime is 668617927. The reversal of 668617918 is 819716866.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 167154478 + ... + 167154481.

It is an arithmetic number, because the mean of its divisors is an integer number (250731720).

Almost surely, 2^668617918 is an apocalyptic number.

668617918 is a deficient number, since it is larger than the sum of its proper divisors (334308962).

668617918 is a wasteful number, since it uses less digits than its factorization.

668617918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334308961.

The product of its digits is 870912, while the sum is 52.

The square root of 668617918 is about 25857.6471860840. The cubic root of 668617918 is about 874.4319220955.

The spelling of 668617918 in words is "six hundred sixty-eight million, six hundred seventeen thousand, nine hundred eighteen".