1805972209 has 4 divisors (see below), whose sum is σ = 1807502580. Its totient is φ = 1804441840.

The previous prime is 1805972159. The next prime is 1805972219. The reversal of 1805972209 is 9022795081.

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 849431025 + 956541184 = 29145^2 + 30928^2 .

It is a cyclic number.

It is not a de Polignac number, because 1805972209 - 2⁷ = 1805972081 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1805972219) 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, 763414 + ... + 765775.

It is an arithmetic number, because the mean of its divisors is an integer number (451875645).

Almost surely, 2^1805972209 is an apocalyptic number.

It is an amenable number.

1805972209 is a deficient number, since it is larger than the sum of its proper divisors (1530371).

1805972209 is a wasteful number, since it uses less digits than its factorization.

1805972209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1530370.

The product of its (nonzero) digits is 90720, while the sum is 43.

The square root of 1805972209 is about 42496.7317449236. The cubic root of 1805972209 is about 1217.7842540082.

The spelling of 1805972209 in words is "one billion, eight hundred five million, nine hundred seventy-two thousand, two hundred nine".