231161221 has 4 divisors (see below), whose sum is σ = 232579552. Its totient is φ = 229742892.

The previous prime is 231161207. The next prime is 231161267. The reversal of 231161221 is 122161132.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-231161221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231131221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 708921 + ... + 709246.

It is an arithmetic number, because the mean of its divisors is an integer number (58144888).

Almost surely, 2^231161221 is an apocalyptic number.

It is an amenable number.

231161221 is a deficient number, since it is larger than the sum of its proper divisors (1418331).

231161221 is a wasteful number, since it uses less digits than its factorization.

231161221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1418330.

The product of its digits is 144, while the sum is 19.

The square root of 231161221 is about 15203.9870099918. The cubic root of 231161221 is about 613.7219551564.

The spelling of 231161221 in words is "two hundred thirty-one million, one hundred sixty-one thousand, two hundred twenty-one".