113831561 has 2 divisors, whose sum is σ = 113831562. Its totient is φ = 113831560.

The previous prime is 113831521. The next prime is 113831563. The reversal of 113831561 is 165138311.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 112254025 + 1577536 = 10595^2 + 1256^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-113831561 is a prime.

Together with 113831563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (113831563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 56915780 + 56915781.

It is an arithmetic number, because the mean of its divisors is an integer number (56915781).

Almost surely, 2^113831561 is an apocalyptic number.

It is an amenable number.

113831561 is a deficient number, since it is larger than the sum of its proper divisors (1).

113831561 is an equidigital number, since it uses as much as digits as its factorization.

113831561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2160, while the sum is 29.

The square root of 113831561 is about 10669.1874573465. The cubic root of 113831561 is about 484.6418314262.

Adding to 113831561 its reverse (165138311), we get a palindrome (278969872).

The spelling of 113831561 in words is "one hundred thirteen million, eight hundred thirty-one thousand, five hundred sixty-one".