1818957809 has 4 divisors (see below), whose sum is σ = 1820900004. Its totient is φ = 1817015616.

The previous prime is 1818957779. The next prime is 1818957817. The reversal of 1818957809 is 9087598181.

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 442176784 + 1376781025 = 21028^2 + 37105^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1818957809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1818957839) 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, 969692 + ... + 971565.

It is an arithmetic number, because the mean of its divisors is an integer number (455225001).

Almost surely, 2^1818957809 is an apocalyptic number.

It is an amenable number.

1818957809 is a deficient number, since it is larger than the sum of its proper divisors (1942195).

1818957809 is an equidigital number, since it uses as much as digits as its factorization.

1818957809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1942194.

The product of its (nonzero) digits is 1451520, while the sum is 56.

The square root of 1818957809 is about 42649.2415993532. The cubic root of 1818957809 is about 1220.6960573788.

The spelling of 1818957809 in words is "one billion, eight hundred eighteen million, nine hundred fifty-seven thousand, eight hundred nine".