1213131111 has 4 divisors (see below), whose sum is σ = 1617508152. Its totient is φ = 808754072.

The previous prime is 1213131109. The next prime is 1213131137. The reversal of 1213131111 is 1111313121.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1213131111 - 2¹ = 1213131109 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1213131211) 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, 202188516 + ... + 202188521.

It is an arithmetic number, because the mean of its divisors is an integer number (404377038).

Almost surely, 2^1213131111 is an apocalyptic number.

1213131111 is a deficient number, since it is larger than the sum of its proper divisors (404377041).

1213131111 is an equidigital number, since it uses as much as digits as its factorization.

1213131111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 404377040.

The product of its digits is 18, while the sum is 15.

The square root of 1213131111 is about 34830.0317398650. The cubic root of 1213131111 is about 1066.5205962848.

Adding to 1213131111 its reverse (1111313121), we get a palindrome (2324444232).

The spelling of 1213131111 in words is "one billion, two hundred thirteen million, one hundred thirty-one thousand, one hundred eleven".