668845549 has 4 divisors (see below), whose sum is σ = 670309564. Its totient is φ = 667381536.

The previous prime is 668845511. The next prime is 668845577. The reversal of 668845549 is 945548866.

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

It can be written as a sum of positive squares in 2 ways, for example, as 360316324 + 308529225 = 18982^2 + 17565^2 .

It is a cyclic number.

It is not a de Polignac number, because 668845549 - 2⁷ = 668845421 is a prime.

It is a super-2 number, since 2×668845549² = 894708736834222802, 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 668845549.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668845649) 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, 731322 + ... + 732235.

It is an arithmetic number, because the mean of its divisors is an integer number (167577391).

Almost surely, 2^668845549 is an apocalyptic number.

It is an amenable number.

668845549 is a deficient number, since it is larger than the sum of its proper divisors (1464015).

668845549 is a wasteful number, since it uses less digits than its factorization.

668845549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1464014.

The product of its digits is 8294400, while the sum is 55.

The square root of 668845549 is about 25862.0484300838. The cubic root of 668845549 is about 874.5311442985.

The spelling of 668845549 in words is "six hundred sixty-eight million, eight hundred forty-five thousand, five hundred forty-nine".