831681561 has 4 divisors (see below), whose sum is σ = 1108908752. Its totient is φ = 554454372.

The previous prime is 831681559. The next prime is 831681563. The reversal of 831681561 is 165186138.

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 an interprime number because it is at equal distance from previous prime (831681559) and next prime (831681563).

It is not a de Polignac number, because 831681561 - 2¹ = 831681559 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (831681563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138613591 + ... + 138613596.

It is an arithmetic number, because the mean of its divisors is an integer number (277227188).

Almost surely, 2^831681561 is an apocalyptic number.

It is an amenable number.

831681561 is a deficient number, since it is larger than the sum of its proper divisors (277227191).

831681561 is a wasteful number, since it uses less digits than its factorization.

831681561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277227190.

The product of its digits is 34560, while the sum is 39.

The square root of 831681561 is about 28838.8897324429. The cubic root of 831681561 is about 940.4138667208.

The spelling of 831681561 in words is "eight hundred thirty-one million, six hundred eighty-one thousand, five hundred sixty-one".