1213256121 has 24 divisors (see below), whose sum is σ = 2052859104. Its totient is φ = 630262080.

The previous prime is 1213256111. The next prime is 1213256147. The reversal of 1213256121 is 1216523121.

It is a happy number.

It is not a de Polignac number, because 1213256121 - 2⁵ = 1213256089 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1213256091 and 1213256100.

It is not an unprimeable number, because it can be changed into a prime (1213256101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 373540 + ... + 376773.

It is an arithmetic number, because the mean of its divisors is an integer number (85535796).

Almost surely, 2^1213256121 is an apocalyptic number.

1213256121 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1213256121 is a deficient number, since it is larger than the sum of its proper divisors (839602983).

1213256121 is a wasteful number, since it uses less digits than its factorization.

1213256121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 750341 (or 750334 counting only the distinct ones).

The product of its digits is 720, while the sum is 24.

The square root of 1213256121 is about 34831.8262656439. The cubic root of 1213256121 is about 1066.5572290827.

Adding to 1213256121 its reverse (1216523121), we get a palindrome (2429779242).

The spelling of 1213256121 in words is "one billion, two hundred thirteen million, two hundred fifty-six thousand, one hundred twenty-one".