1816239121 has 4 divisors (see below), whose sum is σ = 1820128752. Its totient is φ = 1812349492.

The previous prime is 1816239119. The next prime is 1816239157. The reversal of 1816239121 is 1219326181.

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.

It is a cyclic number.

It is not a de Polignac number, because 1816239121 - 2¹ = 1816239119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1816239101) 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, 1944115 + ... + 1945048.

It is an arithmetic number, because the mean of its divisors is an integer number (455032188).

Almost surely, 2^1816239121 is an apocalyptic number.

It is an amenable number.

1816239121 is a deficient number, since it is larger than the sum of its proper divisors (3889631).

1816239121 is an equidigital number, since it uses as much as digits as its factorization.

1816239121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3889630.

The product of its digits is 5184, while the sum is 34.

The square root of 1816239121 is about 42617.3570391220. The cubic root of 1816239121 is about 1220.0875868767.

The spelling of 1816239121 in words is "one billion, eight hundred sixteen million, two hundred thirty-nine thousand, one hundred twenty-one".