381811 has 4 divisors (see below), whose sum is σ = 384192. Its totient is φ = 379432.

The previous prime is 381793. The next prime is 381817. The reversal of 381811 is 118183.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 118183 = 13 ⋅9091.

It is a cyclic number.

It is not a de Polignac number, because 381811 - 2¹⁵ = 349043 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (381817) 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, 931 + ... + 1276.

It is an arithmetic number, because the mean of its divisors is an integer number (96048).

2³⁸¹⁸¹¹ is an apocalyptic number.

381811 is a deficient number, since it is larger than the sum of its proper divisors (2381).

381811 is a wasteful number, since it uses less digits than its factorization.

381811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2380.

The product of its digits is 192, while the sum is 22.

The square root of 381811 is about 617.9085692884. The cubic root of 381811 is about 72.5464466549.

Adding to 381811 its reverse (118183), we get a palindrome (499994).

It can be divided in two parts, 38 and 1811, that added together give a square (1849 = 43²).

The spelling of 381811 in words is "three hundred eighty-one thousand, eight hundred eleven".