681810538020191 has 4 divisors (see below), whose sum is σ = 681839344099800. Its totient is φ = 681781731940584.

The previous prime is 681810538020169. The next prime is 681810538020281. The reversal of 681810538020191 is 191020835018186.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 681810538020191 - 2⁶ = 681810538020127 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681810538020121) 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, 14403004301 + ... + 14403051638.

It is an arithmetic number, because the mean of its divisors is an integer number (170459836024950).

Almost surely, 2^{681810538020191} is an apocalyptic number.

681810538020191 is a deficient number, since it is larger than the sum of its proper divisors (28806079609).

681810538020191 is a wasteful number, since it uses less digits than its factorization.

681810538020191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28806079608.

The product of its (nonzero) digits is 829440, while the sum is 53.

The spelling of 681810538020191 in words is "six hundred eighty-one trillion, eight hundred ten billion, five hundred thirty-eight million, twenty thousand, one hundred ninety-one".