231861 has 16 divisors (see below), whose sum is σ = 361088. Its totient is φ = 129600.

The previous prime is 231859. The next prime is 231871. The reversal of 231861 is 168132.

It is not a de Polignac number, because 231861 - 2¹ = 231859 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

231861 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231821) 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, 1191 + ... + 1371.

It is an arithmetic number, because the mean of its divisors is an integer number (22568).

2²³¹⁸⁶¹ is an apocalyptic number.

231861 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

231861 is a deficient number, since it is larger than the sum of its proper divisors (129227).

231861 is a wasteful number, since it uses less digits than its factorization.

231861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252.

The product of its digits is 288, while the sum is 21.

The square root of 231861 is about 481.5194700113. The cubic root of 231861 is about 61.4340624518.

Adding to 231861 its reverse (168132), we get a palindrome (399993).

It can be divided in two parts, 231 and 861, that multiplied together give a palindrome (198891).

The spelling of 231861 in words is "two hundred thirty-one thousand, eight hundred sixty-one".