231665661 has 6 divisors (see below), whose sum is σ = 334628190. Its totient is φ = 154443768.

The previous prime is 231665641. The next prime is 231665737. The reversal of 231665661 is 166566132.

231665661 is a `hidden beast` number, since 2 + 31 + 66 + 566 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 176624100 + 55041561 = 13290^2 + 7419^2 .

It is not a de Polignac number, because 231665661 - 2⁹ = 231665149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231665641) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12870306 + ... + 12870323.

It is an arithmetic number, because the mean of its divisors is an integer number (55771365).

Almost surely, 2^231665661 is an apocalyptic number.

It is an amenable number.

231665661 is a deficient number, since it is larger than the sum of its proper divisors (102962529).

231665661 is a wasteful number, since it uses less digits than its factorization.

231665661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25740635 (or 25740632 counting only the distinct ones).

The product of its digits is 38880, while the sum is 36.

The square root of 231665661 is about 15220.5670393714. The cubic root of 231665661 is about 614.1680521583.

The spelling of 231665661 in words is "two hundred thirty-one million, six hundred sixty-five thousand, six hundred sixty-one".