1812137809 has 4 divisors (see below), whose sum is σ = 1818586980. Its totient is φ = 1805688640.

The previous prime is 1812137807. The next prime is 1812137827. The reversal of 1812137809 is 9087312181.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 962240400 + 849897409 = 31020^2 + 29153^2 .

It is a cyclic number.

It is not a de Polignac number, because 1812137809 - 2¹ = 1812137807 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1812137807) 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, 3224164 + ... + 3224725.

It is an arithmetic number, because the mean of its divisors is an integer number (454646745).

Almost surely, 2^1812137809 is an apocalyptic number.

It is an amenable number.

1812137809 is a deficient number, since it is larger than the sum of its proper divisors (6449171).

1812137809 is an equidigital number, since it uses as much as digits as its factorization.

1812137809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6449170.

The product of its (nonzero) digits is 24192, while the sum is 40.

The square root of 1812137809 is about 42569.2119847197. The cubic root of 1812137809 is about 1219.1685208291.

The spelling of 1812137809 in words is "one billion, eight hundred twelve million, one hundred thirty-seven thousand, eight hundred nine".