231211993 has 4 divisors (see below), whose sum is σ = 231898420. Its totient is φ = 230525568.

The previous prime is 231211961. The next prime is 231212057. The reversal of 231211993 is 399112132.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 145612489 + 85599504 = 12067^2 + 9252^2 .

It is a cyclic number.

It is not a de Polignac number, because 231211993 - 2⁵ = 231211961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (231211933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 342708 + ... + 343381.

It is an arithmetic number, because the mean of its divisors is an integer number (57974605).

Almost surely, 2^231211993 is an apocalyptic number.

It is an amenable number.

231211993 is a deficient number, since it is larger than the sum of its proper divisors (686427).

231211993 is an equidigital number, since it uses as much as digits as its factorization.

231211993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 686426.

The product of its digits is 2916, while the sum is 31.

The square root of 231211993 is about 15205.6566119323. The cubic root of 231211993 is about 613.7668842755.

The spelling of 231211993 in words is "two hundred thirty-one million, two hundred eleven thousand, nine hundred ninety-three".