1808381 has 4 divisors (see below), whose sum is σ = 1812000. Its totient is φ = 1804764.

The previous prime is 1808377. The next prime is 1808399. The reversal of 1808381 is 1838081.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1838081 = 7 ⋅262583.

It is a cyclic number.

It is not a de Polignac number, because 1808381 - 2² = 1808377 is a prime.

It is a super-2 number, since 2×1808381² = 6540483682322, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1808281) 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, 911 + ... + 2108.

It is an arithmetic number, because the mean of its divisors is an integer number (453000).

2^1808381 is an apocalyptic number.

It is an amenable number.

1808381 is a deficient number, since it is larger than the sum of its proper divisors (3619).

1808381 is an equidigital number, since it uses as much as digits as its factorization.

1808381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3618.

The product of its (nonzero) digits is 1536, while the sum is 29.

The square root of 1808381 is about 1344.7605734851. The cubic root of 1808381 is about 121.8325437039.

The spelling of 1808381 in words is "one million, eight hundred eight thousand, three hundred eighty-one".