231987181 has 2 divisors, whose sum is σ = 231987182. Its totient is φ = 231987180.

The previous prime is 231987179. The next prime is 231987187. The reversal of 231987181 is 181789132.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 220997956 + 10989225 = 14866^2 + 3315^2 .

It is a cyclic number.

It is not a de Polignac number, because 231987181 - 2¹ = 231987179 is a prime.

It is a super-2 number, since 2×231987181² = 107636104296653522, which contains 22 as substring.

Together with 231987179, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (231987187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115993590 + 115993591.

It is an arithmetic number, because the mean of its divisors is an integer number (115993591).

Almost surely, 2^231987181 is an apocalyptic number.

It is an amenable number.

231987181 is a deficient number, since it is larger than the sum of its proper divisors (1).

231987181 is an equidigital number, since it uses as much as digits as its factorization.

231987181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 40.

The square root of 231987181 is about 15231.1254016241. The cubic root of 231987181 is about 614.4520476789.

The spelling of 231987181 in words is "two hundred thirty-one million, nine hundred eighty-seven thousand, one hundred eighty-one".