1231312221 has 24 divisors (see below), whose sum is σ = 1811628000. Its totient is φ = 805742496.

The previous prime is 1231312217. The next prime is 1231312259. The reversal of 1231312221 is 1222131321.

It is not a de Polignac number, because 1231312221 - 2² = 1231312217 is a prime.

It is a super-2 number, since 2×1231312221² = 3032259571167905682, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1231312194 and 1231312203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231312211) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 112030 + ... + 122528.

It is an arithmetic number, because the mean of its divisors is an integer number (75484500).

Almost surely, 2^1231312221 is an apocalyptic number.

It is an amenable number.

1231312221 is a deficient number, since it is larger than the sum of its proper divisors (580315779).

1231312221 is a wasteful number, since it uses less digits than its factorization.

1231312221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10745 (or 10742 counting only the distinct ones).

The product of its digits is 144, while the sum is 18.

The square root of 1231312221 is about 35090.0587203840. The cubic root of 1231312221 is about 1071.8221553403.

Adding to 1231312221 its reverse (1222131321), we get a palindrome (2453443542).

Subtracting from 1231312221 its reverse (1222131321), we obtain a square (9180900 = 3030²).

The spelling of 1231312221 in words is "one billion, two hundred thirty-one million, three hundred twelve thousand, two hundred twenty-one".