681591863 has 4 divisors (see below), whose sum is σ = 721685520. Its totient is φ = 641498208.

The previous prime is 681591853. The next prime is 681591877. The reversal of 681591863 is 368195186.

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 681591863 - 2²⁰ = 680543287 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 (681591853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20046803 + ... + 20046836.

It is an arithmetic number, because the mean of its divisors is an integer number (180421380).

Almost surely, 2^681591863 is an apocalyptic number.

681591863 is a deficient number, since it is larger than the sum of its proper divisors (40093657).

681591863 is a wasteful number, since it uses less digits than its factorization.

681591863 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40093656.

The product of its digits is 311040, while the sum is 47.

The square root of 681591863 is about 26107.3143582407. The cubic root of 681591863 is about 880.0515908975.

The spelling of 681591863 in words is "six hundred eighty-one million, five hundred ninety-one thousand, eight hundred sixty-three".