231981161 has 2 divisors, whose sum is σ = 231981162. Its totient is φ = 231981160.

The previous prime is 231981107. The next prime is 231981163. The reversal of 231981161 is 161189132.

231981161 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 140185600 + 91795561 = 11840^2 + 9581^2 .

It is a cyclic number.

It is not a de Polignac number, because 231981161 - 2¹⁰ = 231980137 is a prime.

Together with 231981163, 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 (231981163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115990580 + 115990581.

It is an arithmetic number, because the mean of its divisors is an integer number (115990581).

Almost surely, 2^231981161 is an apocalyptic number.

It is an amenable number.

231981161 is a deficient number, since it is larger than the sum of its proper divisors (1).

231981161 is an equidigital number, since it uses as much as digits as its factorization.

231981161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 32.

The square root of 231981161 is about 15230.9277787008. The cubic root of 231981161 is about 614.4467326822.

The spelling of 231981161 in words is "two hundred thirty-one million, nine hundred eighty-one thousand, one hundred sixty-one".