231445221 has 16 divisors (see below), whose sum is σ = 360881664. Its totient is φ = 129178224.

The previous prime is 231445217. The next prime is 231445241. The reversal of 231445221 is 122544132.

It is not a de Polignac number, because 231445221 - 2² = 231445217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 231445191 and 231445200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231445241) 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, 127251 + ... + 129056.

It is an arithmetic number, because the mean of its divisors is an integer number (22555104).

Almost surely, 2^231445221 is an apocalyptic number.

231445221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

231445221 is a deficient number, since it is larger than the sum of its proper divisors (129436443).

231445221 is a wasteful number, since it uses less digits than its factorization.

231445221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256360.

The product of its digits is 1920, while the sum is 24.

The square root of 231445221 is about 15213.3237985655. The cubic root of 231445221 is about 613.9731877578.

Adding to 231445221 its reverse (122544132), we get a palindrome (353989353).

The spelling of 231445221 in words is "two hundred thirty-one million, four hundred forty-five thousand, two hundred twenty-one".