231691131 has 16 divisors (see below), whose sum is σ = 392281600. Its totient is φ = 132394824.

The previous prime is 231691129. The next prime is 231691139. The reversal of 231691131 is 131196132.

It is not a de Polignac number, because 231691131 - 2¹ = 231691129 is a prime.

It is a super-2 number, since 2×231691131² = 107361560368118322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 231691095 and 231691104.

It is not an unprimeable number, because it can be changed into a prime (231691139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 612751 + ... + 613128.

It is an arithmetic number, because the mean of its divisors is an integer number (24517600).

Almost surely, 2^231691131 is an apocalyptic number.

231691131 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

231691131 is a deficient number, since it is larger than the sum of its proper divisors (160590469).

231691131 is a wasteful number, since it uses less digits than its factorization.

231691131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1225895 (or 1225889 counting only the distinct ones).

The product of its digits is 972, while the sum is 27.

The square root of 231691131 is about 15221.4037131928. The cubic root of 231691131 is about 614.1905591438.

The spelling of 231691131 in words is "two hundred thirty-one million, six hundred ninety-one thousand, one hundred thirty-one".