231891985 has 16 divisors (see below), whose sum is σ = 317305296. Its totient is φ = 161169408.

The previous prime is 231891953. The next prime is 231892021. The reversal of 231891985 is 589198132.

It is a Cunningham number, because it is equal to 15228²+1.

It can be written as a sum of positive squares in 8 ways, for example, as 1 + 231891984 = 1^2 + 15228^2 .

It is a cyclic number.

It is not a de Polignac number, because 231891985 - 2⁵ = 231891953 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 103824 + ... + 106033.

It is an arithmetic number, because the mean of its divisors is an integer number (19831581).

Almost surely, 2^231891985 is an apocalyptic number.

It is an amenable number.

231891985 is a deficient number, since it is larger than the sum of its proper divisors (85413311).

231891985 is a wasteful number, since it uses less digits than its factorization.

231891985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209892.

The product of its digits is 155520, while the sum is 46.

The square root of 231891985 is about 15228.0000328343. Note that the first 4 decimals coincide. The cubic root of 231891985 is about 614.3679893276.

The spelling of 231891985 in words is "two hundred thirty-one million, eight hundred ninety-one thousand, nine hundred eighty-five".