381821 has 8 divisors (see below), whose sum is σ = 421824. Its totient is φ = 342720.

The previous prime is 381817. The next prime is 381841. The reversal of 381821 is 128183.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 381821 - 2² = 381817 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 (381841) 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 7 ways as a sum of consecutive naturals, for example, 965 + ... + 1301.

It is an arithmetic number, because the mean of its divisors is an integer number (52728).

2³⁸¹⁸²¹ is an apocalyptic number.

It is an amenable number.

381821 is a deficient number, since it is larger than the sum of its proper divisors (40003).

381821 is a wasteful number, since it uses less digits than its factorization.

381821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 451.

The product of its digits is 384, while the sum is 23.

The square root of 381821 is about 617.9166610474. The cubic root of 381821 is about 72.5470800032.

It can be divided in two parts, 38182 and 1, that added together give a palindrome (38183).

The spelling of 381821 in words is "three hundred eighty-one thousand, eight hundred twenty-one".