818681 has 4 divisors (see below), whose sum is σ = 832164. Its totient is φ = 805200.

The previous prime is 818659. The next prime is 818683. The reversal of 818681 is 186818.

It is a happy number.

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 384400 + 434281 = 620^2 + 659^2 .

It is not a de Polignac number, because 818681 - 2¹⁴ = 802297 is a prime.

It is a super-2 number, since 2×818681² = 1340477159522, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (818683) 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, 6650 + ... + 6771.

It is an arithmetic number, because the mean of its divisors is an integer number (208041).

2⁸¹⁸⁶⁸¹ is an apocalyptic number.

It is an amenable number.

818681 is a deficient number, since it is larger than the sum of its proper divisors (13483).

818681 is a wasteful number, since it uses less digits than its factorization.

818681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13482.

The product of its digits is 3072, while the sum is 32.

The square root of 818681 is about 904.8099247908. The cubic root of 818681 is about 93.5488034848.

The spelling of 818681 in words is "eight hundred eighteen thousand, six hundred eighty-one".