668591742690 has 24 divisors (see below), whose sum is σ = 1738338531228. Its totient is φ = 178291131360.

The previous prime is 668591742661. The next prime is 668591742751. The reversal of 668591742690 is 96247195866.

668591742690 is a `hidden beast` number, since 6 + 68 + 59 + 17 + 426 + 90 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 648390521529 + 20201221161 = 805227^2 + 142131^2 .

It is a super-2 number, since 2×668591742690² (a number of 24 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (63) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3714398481 + ... + 3714398660.

Almost surely, 2^668591742690 is an apocalyptic number.

668591742690 is an abundant number, since it is smaller than the sum of its proper divisors (1069746788538).

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

668591742690 is a wasteful number, since it uses less digits than its factorization.

668591742690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7428797154 (or 7428797151 counting only the distinct ones).

The product of its (nonzero) digits is 39191040, while the sum is 63.

The spelling of 668591742690 in words is "six hundred sixty-eight billion, five hundred ninety-one million, seven hundred forty-two thousand, six hundred ninety".