1806381 has 20 divisors (see below), whose sum is σ = 2795100. Its totient is φ = 1161216.

The previous prime is 1806379. The next prime is 1806383. The reversal of 1806381 is 1836081.

It is an interprime number because it is at equal distance from previous prime (1806379) and next prime (1806383).

It can be written as a sum of positive squares in 2 ways, for example, as 826281 + 980100 = 909^2 + 990^2 .

It is not a de Polignac number, because 1806381 - 2¹ = 1806379 is a prime.

It is a super-2 number, since 2×1806381² = 6526024634322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1806383) 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, 1965 + ... + 2733.

It is an arithmetic number, because the mean of its divisors is an integer number (139755).

2^1806381 is an apocalyptic number.

It is an amenable number.

1806381 is a deficient number, since it is larger than the sum of its proper divisors (988719).

1806381 is an equidigital number, since it uses as much as digits as its factorization.

1806381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 810 (or 801 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 1806381 is about 1344.0167409672. The cubic root of 1806381 is about 121.7876130964.

It can be divided in two parts, 1806 and 381, that added together give a 7-th power (2187 = 3⁷).

The spelling of 1806381 in words is "one million, eight hundred six thousand, three hundred eighty-one".