820381 has 4 divisors (see below), whose sum is σ = 848700. Its totient is φ = 792064.

The previous prime is 820367. The next prime is 820399. The reversal of 820381 is 183028.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 632025 + 188356 = 795^2 + 434^2 .

It is a cyclic number.

It is not a de Polignac number, because 820381 - 2⁵ = 820349 is a prime.

It is a super-2 number, since 2×820381² = 1346049970322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820321) 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, 14116 + ... + 14173.

It is an arithmetic number, because the mean of its divisors is an integer number (212175).

2⁸²⁰³⁸¹ is an apocalyptic number.

It is an amenable number.

820381 is a deficient number, since it is larger than the sum of its proper divisors (28319).

820381 is a wasteful number, since it uses less digits than its factorization.

820381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28318.

The product of its (nonzero) digits is 384, while the sum is 22.

The square root of 820381 is about 905.7488614401. The cubic root of 820381 is about 93.6135104198.

The spelling of 820381 in words is "eight hundred twenty thousand, three hundred eighty-one".