1818181809 has 20 divisors (see below), whose sum is σ = 2834141376. Its totient is φ = 1159419096.

The previous prime is 1818181787. The next prime is 1818181817. The reversal of 1818181809 is 9081818181.

It is not a de Polignac number, because 1818181809 - 2⁷ = 1818181681 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (1818181889) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 486109 + ... + 489834.

Almost surely, 2^1818181809 is an apocalyptic number.

It is an amenable number.

1818181809 is a deficient number, since it is larger than the sum of its proper divisors (1015959567).

1818181809 is an equidigital number, since it uses as much as digits as its factorization.

1818181809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 975978 (or 975969 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 45.

The square root of 1818181809 is about 42640.1431634557. The cubic root of 1818181809 is about 1220.5224424157.

The spelling of 1818181809 in words is "one billion, eight hundred eighteen million, one hundred eighty-one thousand, eight hundred nine".