668643891400 has 24 divisors (see below), whose sum is σ = 1554597047970. Its totient is φ = 267457556480.

The previous prime is 668643891389. The next prime is 668643891401. The reversal of 668643891400 is 4198346866.

It can be written as a sum of positive squares in 3 ways, for example, as 610939203876 + 57704687524 = 781626^2 + 240218^2 .

It is not an unprimeable number, because it can be changed into a prime (668643891401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1671609529 + ... + 1671609928.

Almost surely, 2^668643891400 is an apocalyptic number.

It is an amenable number.

668643891400 is an abundant number, since it is smaller than the sum of its proper divisors (885953156570).

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

668643891400 is a wasteful number, since it uses less digits than its factorization.

668643891400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3343219473 (or 3343219464 counting only the distinct ones).

The product of its (nonzero) digits is 5971968, while the sum is 55.

The spelling of 668643891400 in words is "six hundred sixty-eight billion, six hundred forty-three million, eight hundred ninety-one thousand, four hundred".