231505861 has 16 divisors (see below), whose sum is σ = 252428800. Its totient is φ = 211727520.

The previous prime is 231505853. The next prime is 231505873. The reversal of 231505861 is 168505132.

It is not a de Polignac number, because 231505861 - 2³ = 231505853 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231505831) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 565825 + ... + 566233.

It is an arithmetic number, because the mean of its divisors is an integer number (15776800).

Almost surely, 2^231505861 is an apocalyptic number.

It is an amenable number.

231505861 is a deficient number, since it is larger than the sum of its proper divisors (20922939).

231505861 is an frugal number, since it uses more digits than its factorization.

231505861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521 (or 459 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 31.

The square root of 231505861 is about 15215.3166578944. The cubic root of 231505861 is about 614.0268045961.

The spelling of 231505861 in words is "two hundred thirty-one million, five hundred five thousand, eight hundred sixty-one".