231535661 has 4 divisors (see below), whose sum is σ = 264612192. Its totient is φ = 198459132.

The previous prime is 231535627. The next prime is 231535679. The reversal of 231535661 is 166535132.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 231535661 - 2¹⁸ = 231273517 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 (231535861) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16538255 + ... + 16538268.

It is an arithmetic number, because the mean of its divisors is an integer number (66153048).

Almost surely, 2^231535661 is an apocalyptic number.

It is an amenable number.

231535661 is a deficient number, since it is larger than the sum of its proper divisors (33076531).

231535661 is an equidigital number, since it uses as much as digits as its factorization.

231535661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33076530.

The product of its digits is 16200, while the sum is 32.

The square root of 231535661 is about 15216.2959027485. The cubic root of 231535661 is about 614.0531498092.

The spelling of 231535661 in words is "two hundred thirty-one million, five hundred thirty-five thousand, six hundred sixty-one".