1811381 has 16 divisors (see below), whose sum is σ = 2177280. Its totient is φ = 1485120.

The previous prime is 1811377. The next prime is 1811387. The reversal of 1811381 is 1831181.

It is not a de Polignac number, because 1811381 - 2² = 1811377 is a prime.

It is a super-2 number, since 2×1811381² = 6562202254322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1811387) 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 15 ways as a sum of consecutive naturals, for example, 7460 + ... + 7698.

It is an arithmetic number, because the mean of its divisors is an integer number (136080).

2^1811381 is an apocalyptic number.

1811381 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1811381 is a deficient number, since it is larger than the sum of its proper divisors (365899).

1811381 is a wasteful number, since it uses less digits than its factorization.

1811381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316.

The product of its digits is 192, while the sum is 23.

The square root of 1811381 is about 1345.8755514534. The cubic root of 1811381 is about 121.8998775426.

The spelling of 1811381 in words is "one million, eight hundred eleven thousand, three hundred eighty-one".