668591646 has 32 divisors (see below), whose sum is σ = 1468765440. Its totient is φ = 201953664.

The previous prime is 668591641. The next prime is 668591653. The reversal of 668591646 is 646195866.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668591641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 124875 + ... + 130118.

It is an arithmetic number, because the mean of its divisors is an integer number (45898920).

Almost surely, 2^668591646 is an apocalyptic number.

668591646 is an abundant number, since it is smaller than the sum of its proper divisors (800173794).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

668591646 is a wasteful number, since it uses less digits than its factorization.

668591646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255040.

The product of its digits is 1866240, while the sum is 51.

The square root of 668591646 is about 25857.1391689027. The cubic root of 668591646 is about 874.4204689293.

The spelling of 668591646 in words is "six hundred sixty-eight million, five hundred ninety-one thousand, six hundred forty-six".