816381 has 6 divisors (see below), whose sum is σ = 1179230. Its totient is φ = 544248.

The previous prime is 816377. The next prime is 816401. The reversal of 816381 is 183618.

It can be written as a sum of positive squares in only one way, i.e., 793881 + 22500 = 891^2 + 150^2 .

It is not a de Polignac number, because 816381 - 2² = 816377 is a prime.

It is a super-2 number, since 2×816381² = 1332955874322, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816341) 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 5 ways as a sum of consecutive naturals, for example, 45346 + ... + 45363.

2⁸¹⁶³⁸¹ is an apocalyptic number.

It is an amenable number.

816381 is a deficient number, since it is larger than the sum of its proper divisors (362849).

816381 is a wasteful number, since it uses less digits than its factorization.

816381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90715 (or 90712 counting only the distinct ones).

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

The square root of 816381 is about 903.5380456849. The cubic root of 816381 is about 93.4611160725.

Adding to 816381 its reverse (183618), we get a palindrome (999999).

The spelling of 816381 in words is "eight hundred sixteen thousand, three hundred eighty-one".