681517717861 has 4 divisors (see below), whose sum is σ = 686883999232. Its totient is φ = 676151436492.

The previous prime is 681517717847. The next prime is 681517717871. The reversal of 681517717861 is 168717715186.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 681517717861 - 2⁷ = 681517717733 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 681517717796 and 681517717805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681517717871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2683140495 + ... + 2683140748.

It is an arithmetic number, because the mean of its divisors is an integer number (171720999808).

Almost surely, 2^681517717861 is an apocalyptic number.

It is an amenable number.

681517717861 is a deficient number, since it is larger than the sum of its proper divisors (5366281371).

681517717861 is a wasteful number, since it uses less digits than its factorization.

681517717861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5366281370.

The product of its digits is 3951360, while the sum is 58.

The spelling of 681517717861 in words is "six hundred eighty-one billion, five hundred seventeen million, seven hundred seventeen thousand, eight hundred sixty-one".