681945566691 has 4 divisors (see below), whose sum is σ = 909260755592. Its totient is φ = 454630377792.

The previous prime is 681945566641. The next prime is 681945566737. The reversal of 681945566691 is 196665549186.

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

It is not a de Polignac number, because 681945566691 - 2⁷ = 681945566563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (681945566641) 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, 113657594446 + ... + 113657594451.

It is an arithmetic number, because the mean of its divisors is an integer number (227315188898).

Almost surely, 2^681945566691 is an apocalyptic number.

681945566691 is a deficient number, since it is larger than the sum of its proper divisors (227315188901).

681945566691 is a wasteful number, since it uses less digits than its factorization.

681945566691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 227315188900.

The product of its digits is 83980800, while the sum is 66.

The spelling of 681945566691 in words is "six hundred eighty-one billion, nine hundred forty-five million, five hundred sixty-six thousand, six hundred ninety-one".