1213121111 has 8 divisors (see below), whose sum is σ = 1229012400. Its totient is φ = 1197260352.

The previous prime is 1213121099. The next prime is 1213121113. The reversal of 1213121111 is 1111213121.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1213121111 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1213121113) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78665 + ... + 92813.

It is an arithmetic number, because the mean of its divisors is an integer number (153626550).

Almost surely, 2^1213121111 is an apocalyptic number.

1213121111 is a deficient number, since it is larger than the sum of its proper divisors (15891289).

1213121111 is a wasteful number, since it uses less digits than its factorization.

1213121111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15265.

The product of its digits is 12, while the sum is 14.

The square root of 1213121111 is about 34829.8881852928. Note that the first 3 decimals coincide. The cubic root of 1213121111 is about 1066.5176657867.

Adding to 1213121111 its reverse (1111213121), we get a palindrome (2324334232).

It can be divided in two parts, 1213121 and 111, that multiplied together give a palindrome (134656431).

The spelling of 1213121111 in words is "one billion, two hundred thirteen million, one hundred twenty-one thousand, one hundred eleven".