1812543121 has 4 divisors (see below), whose sum is σ = 1819231744. Its totient is φ = 1805854500.

The previous prime is 1812543113. The next prime is 1812543157. The reversal of 1812543121 is 1213452181.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1213452181 = 193 ⋅6287317.

It is a cyclic number.

It is not a de Polignac number, because 1812543121 - 2³ = 1812543113 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1812543121.

It is not an unprimeable number, because it can be changed into a prime (1812543191) 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 3 ways as a sum of consecutive naturals, for example, 3343905 + ... + 3344446.

It is an arithmetic number, because the mean of its divisors is an integer number (454807936).

Almost surely, 2^1812543121 is an apocalyptic number.

It is an amenable number.

1812543121 is a deficient number, since it is larger than the sum of its proper divisors (6688623).

1812543121 is an equidigital number, since it uses as much as digits as its factorization.

1812543121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6688622.

The product of its digits is 1920, while the sum is 28.

The square root of 1812543121 is about 42573.9723422656. The cubic root of 1812543121 is about 1219.2594092065.

The spelling of 1812543121 in words is "one billion, eight hundred twelve million, five hundred forty-three thousand, one hundred twenty-one".