668466210640 has 20 divisors (see below), whose sum is σ = 1554183939924. Its totient is φ = 267386484224.

The previous prime is 668466210593. The next prime is 668466210683. The reversal of 668466210640 is 46012664866.

668466210640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 306269269056 + 362196941584 = 553416^2 + 601828^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-3 number, since 3×668466210640³ (a number of 36 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4177913737 + ... + 4177913896.

Almost surely, 2^668466210640 is an apocalyptic number.

It is an amenable number.

668466210640 is an abundant number, since it is smaller than the sum of its proper divisors (885717729284).

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

668466210640 is a wasteful number, since it uses less digits than its factorization.

668466210640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8355827646 (or 8355827640 counting only the distinct ones).

The product of its (nonzero) digits is 1990656, while the sum is 49.

The spelling of 668466210640 in words is "six hundred sixty-eight billion, four hundred sixty-six million, two hundred ten thousand, six hundred forty".