668221628 has 12 divisors (see below), whose sum is σ = 1200993192. Its totient is φ = 325080720.

The previous prime is 668221627. The next prime is 668221639. The reversal of 668221628 is 826122866.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668221627) 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, 2257358 + ... + 2257653.

It is an arithmetic number, because the mean of its divisors is an integer number (100082766).

Almost surely, 2^668221628 is an apocalyptic number.

It is an amenable number.

668221628 is a deficient number, since it is larger than the sum of its proper divisors (532771564).

668221628 is a wasteful number, since it uses less digits than its factorization.

668221628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4515052 (or 4515050 counting only the distinct ones).

The product of its digits is 110592, while the sum is 41.

The square root of 668221628 is about 25849.9831334568. The cubic root of 668221628 is about 874.2591292830.

The spelling of 668221628 in words is "six hundred sixty-eight million, two hundred twenty-one thousand, six hundred twenty-eight".