668791635461 has 4 divisors (see below), whose sum is σ = 675413334924. Its totient is φ = 662169936000.

The previous prime is 668791635451. The next prime is 668791635481. The reversal of 668791635461 is 164536197866.

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 645411390625 + 23380244836 = 803375^2 + 152906^2 .

It is a cyclic number.

It is not a de Polignac number, because 668791635461 - 2¹⁴ = 668791619077 is a prime.

It is a super-2 number, since 2×668791635461² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 668791635394 and 668791635403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668791635431) 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, 3310849580 + ... + 3310849781.

It is an arithmetic number, because the mean of its divisors is an integer number (168853333731).

Almost surely, 2^668791635461 is an apocalyptic number.

It is an amenable number.

668791635461 is a deficient number, since it is larger than the sum of its proper divisors (6621699463).

668791635461 is a wasteful number, since it uses less digits than its factorization.

668791635461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6621699462.

The product of its digits is 39191040, while the sum is 62.

The spelling of 668791635461 in words is "six hundred sixty-eight billion, seven hundred ninety-one million, six hundred thirty-five thousand, four hundred sixty-one".