668221594 has 4 divisors (see below), whose sum is σ = 1002332394. Its totient is φ = 334110796.

The previous prime is 668221573. The next prime is 668221613. The reversal of 668221594 is 495122866.

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

It can be written as a sum of positive squares in only one way, i.e., 491198569 + 177023025 = 22163^2 + 13305^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 668221594.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 167055397 + ... + 167055400.

Almost surely, 2^668221594 is an apocalyptic number.

668221594 is a deficient number, since it is larger than the sum of its proper divisors (334110800).

668221594 is a wasteful number, since it uses less digits than its factorization.

668221594 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334110799.

The product of its digits is 207360, while the sum is 43.

The square root of 668221594 is about 25849.9824758161. The cubic root of 668221594 is about 874.2591144552.

The spelling of 668221594 in words is "six hundred sixty-eight million, two hundred twenty-one thousand, five hundred ninety-four".