668415981 has 8 divisors (see below), whose sum is σ = 891522720. Its totient is φ = 445459952.

The previous prime is 668415967. The next prime is 668416003. The reversal of 668415981 is 189514866.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668415981 is a prime.

It is a super-2 number, since 2×668415981² = 893559847312384722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 668415981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668415931) 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, 26886 + ... + 45383.

It is an arithmetic number, because the mean of its divisors is an integer number (111440340).

Almost surely, 2^668415981 is an apocalyptic number.

It is an amenable number.

668415981 is a deficient number, since it is larger than the sum of its proper divisors (223106739).

668415981 is a wasteful number, since it uses less digits than its factorization.

668415981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75355.

The product of its digits is 414720, while the sum is 48.

The square root of 668415981 is about 25853.7421082520. The cubic root of 668415981 is about 874.3438808119.

The spelling of 668415981 in words is "six hundred sixty-eight million, four hundred fifteen thousand, nine hundred eighty-one".