231231661 has 4 divisors (see below), whose sum is σ = 234399292. Its totient is φ = 228064032.

The previous prime is 231231613. The next prime is 231231731. The reversal of 231231661 is 166132132.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 160503561 + 70728100 = 12669^2 + 8410^2 .

It is a cyclic number.

It is not a de Polignac number, because 231231661 - 2²⁷ = 97013933 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231231061) 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, 1583706 + ... + 1583851.

It is an arithmetic number, because the mean of its divisors is an integer number (58599823).

Almost surely, 2^231231661 is an apocalyptic number.

It is an amenable number.

231231661 is a deficient number, since it is larger than the sum of its proper divisors (3167631).

231231661 is an equidigital number, since it uses as much as digits as its factorization.

231231661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3167630.

The product of its digits is 1296, while the sum is 25.

The square root of 231231661 is about 15206.3033311847. The cubic root of 231231661 is about 613.7842870994.

Adding to 231231661 its reverse (166132132), we get a palindrome (397363793).

The spelling of 231231661 in words is "two hundred thirty-one million, two hundred thirty-one thousand, six hundred sixty-one".