231081561 has 12 divisors (see below), whose sum is σ = 353419092. Its totient is φ = 144992256.

The previous prime is 231081551. The next prime is 231081569. The reversal of 231081561 is 165180132.

231081561 is a `hidden beast` number, since 23 + 1 + 0 + 81 + 561 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 153289161 + 77792400 = 12381^2 + 8820^2 .

It is not a de Polignac number, because 231081561 - 2¹³ = 231073369 is a prime.

It is not an unprimeable number, because it can be changed into a prime (231081569) 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 11 ways as a sum of consecutive naturals, for example, 755016 + ... + 755321.

It is an arithmetic number, because the mean of its divisors is an integer number (29451591).

Almost surely, 2^231081561 is an apocalyptic number.

It is an amenable number.

231081561 is a deficient number, since it is larger than the sum of its proper divisors (122337531).

231081561 is a wasteful number, since it uses less digits than its factorization.

231081561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1510360 (or 1510357 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 231081561 is about 15201.3670766810. The cubic root of 231081561 is about 613.6514492303.

The spelling of 231081561 in words is "two hundred thirty-one million, eighty-one thousand, five hundred sixty-one".