1211311231 has 4 divisors (see below), whose sum is σ = 1304489032. Its totient is φ = 1118133432.

The previous prime is 1211311219. The next prime is 1211311259. The reversal of 1211311231 is 1321131121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1321131121 = 109 ⋅12120469.

It is not a de Polignac number, because 1211311231 - 2⁷ = 1211311103 is a prime.

It is a super-2 number, since 2×1211311231² = 2934549796693470722, 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 (1211311201) 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, 46588881 + ... + 46588906.

It is an arithmetic number, because the mean of its divisors is an integer number (326122258).

Almost surely, 2^1211311231 is an apocalyptic number.

1211311231 is a deficient number, since it is larger than the sum of its proper divisors (93177801).

1211311231 is an equidigital number, since it uses as much as digits as its factorization.

1211311231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93177800.

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

The square root of 1211311231 is about 34803.8967789528. The cubic root of 1211311231 is about 1065.9870153546.

Adding to 1211311231 its reverse (1321131121), we get a palindrome (2532442352).

The spelling of 1211311231 in words is "one billion, two hundred eleven million, three hundred eleven thousand, two hundred thirty-one".