1213111231 has 4 divisors (see below), whose sum is σ = 1213218864. Its totient is φ = 1213003600.

The previous prime is 1213111217. The next prime is 1213111243. The reversal of 1213111231 is 1321113121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1321113121 = 4441 ⋅297481.

It is a cyclic number.

It is not a de Polignac number, because 1213111231 - 2⁹ = 1213110719 is a prime.

It is a super-2 number, since 2×1213111231² = 2943277717556670722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1213111201) 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, 34630 + ... + 60211.

It is an arithmetic number, because the mean of its divisors is an integer number (303304716).

Almost surely, 2^1213111231 is an apocalyptic number.

1213111231 is a deficient number, since it is larger than the sum of its proper divisors (107633).

1213111231 is an equidigital number, since it uses as much as digits as its factorization.

1213111231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107632.

The product of its digits is 36, while the sum is 16.

The square root of 1213111231 is about 34829.7463527945. The cubic root of 1213111231 is about 1066.5147704387.

Adding to 1213111231 its reverse (1321113121), we get a palindrome (2534224352).

The spelling of 1213111231 in words is "one billion, two hundred thirteen million, one hundred eleven thousand, two hundred thirty-one".