1813909 has 6 divisors (see below), whose sum is σ = 1842530. Its totient is φ = 1785696.

The previous prime is 1813901. The next prime is 1813913. The reversal of 1813909 is 9093181.

It can be written as a sum of positive squares in 3 ways, for example, as 180625 + 1633284 = 425^2 + 1278^2 .

It is not a de Polignac number, because 1813909 - 2³ = 1813901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1813901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7807 + ... + 8035.

2^1813909 is an apocalyptic number.

It is an amenable number.

1813909 is a deficient number, since it is larger than the sum of its proper divisors (28621).

1813909 is an frugal number, since it uses more digits than its factorization.

1813909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407 (or 318 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 1813909 is about 1346.8143895875. The cubic root of 1813909 is about 121.9565598276.

The spelling of 1813909 in words is "one million, eight hundred thirteen thousand, nine hundred nine".