668238815 has 4 divisors (see below), whose sum is σ = 801886584. Its totient is φ = 534591048.

The previous prime is 668238811. The next prime is 668238829. The reversal of 668238815 is 518832866.

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

It is a cyclic number.

It is not a de Polignac number, because 668238815 - 2² = 668238811 is a prime.

It is a super-2 number, since 2×668238815² = 893086227745208450, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 668238815.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668238811) 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, 66823877 + ... + 66823886.

It is an arithmetic number, because the mean of its divisors is an integer number (200471646).

Almost surely, 2^668238815 is an apocalyptic number.

668238815 is a deficient number, since it is larger than the sum of its proper divisors (133647769).

668238815 is a wasteful number, since it uses less digits than its factorization.

668238815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133647768.

The product of its digits is 552960, while the sum is 47.

The square root of 668238815 is about 25850.3155686734. The cubic root of 668238815 is about 874.2666246819.

The spelling of 668238815 in words is "six hundred sixty-eight million, two hundred thirty-eight thousand, eight hundred fifteen".