2156312121 has 16 divisors (see below), whose sum is σ = 2921315904. Its totient is φ = 1414473984.

The previous prime is 2156312087. The next prime is 2156312129. The reversal of 2156312121 is 1212136512.

It is a happy number.

It is not a de Polignac number, because 2156312121 - 2³⁰ = 1082570297 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2156312091 and 2156312100.

It is not an unprimeable number, because it can be changed into a prime (2156312129) 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 15 ways as a sum of consecutive naturals, for example, 185925 + ... + 197181.

It is an arithmetic number, because the mean of its divisors is an integer number (182582244).

Almost surely, 2^2156312121 is an apocalyptic number.

It is an amenable number.

2156312121 is a deficient number, since it is larger than the sum of its proper divisors (765003783).

2156312121 is a wasteful number, since it uses less digits than its factorization.

2156312121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12280.

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

The square root of 2156312121 is about 46436.1079441419. The cubic root of 2156312121 is about 1291.9247195240.

Adding to 2156312121 its reverse (1212136512), we get a palindrome (3368448633).

The spelling of 2156312121 in words is "two billion, one hundred fifty-six million, three hundred twelve thousand, one hundred twenty-one".