813889 has 4 divisors (see below), whose sum is σ = 835924. Its totient is φ = 791856.

The previous prime is 813871. The next prime is 813893. The reversal of 813889 is 988318.

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 640000 + 173889 = 800^2 + 417^2 .

It is a cyclic number.

It is not a de Polignac number, because 813889 - 2⁹ = 813377 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 21997 = 813889 / (8 + 1 + 3 + 8 + 8 + 9).

It is a Duffinian number.

813889 is a lucky number.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (813829) 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, 10962 + ... + 11035.

It is an arithmetic number, because the mean of its divisors is an integer number (208981).

2⁸¹³⁸⁸⁹ is an apocalyptic number.

It is an amenable number.

813889 is a deficient number, since it is larger than the sum of its proper divisors (22035).

813889 is a wasteful number, since it uses less digits than its factorization.

813889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22034.

The product of its digits is 13824, while the sum is 37.

The square root of 813889 is about 902.1579684290. The cubic root of 813889 is about 93.3659225764.

The spelling of 813889 in words is "eight hundred thirteen thousand, eight hundred eighty-nine".