809919 has 28 divisors (see below), whose sum is σ = 1337832. Its totient is φ = 486000.

The previous prime is 809917. The next prime is 809929. The reversal of 809919 is 919908.

It is not a de Polignac number, because 809919 - 2¹ = 809917 is a prime.

It is a super-2 number, since 2×809919² = 1311937573122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (809917) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 7969 + ... + 8069.

809919 is a Friedman number, since it can be written as 909*891, using all its digits and the basic arithmetic operations.

It is a vampire number, since it can be written as 891 ⋅ 909 (with its own digits).

2⁸⁰⁹⁹¹⁹ is an apocalyptic number.

809919 is a deficient number, since it is larger than the sum of its proper divisors (527913).

809919 is a wasteful number, since it uses less digits than its factorization.

809919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130 (or 115 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 36.

The square root of 809919 is about 899.9549988749. The cubic root of 809919 is about 93.2138678425.

It can be divided in two parts, 8099 and 19, that added together give a palindrome (8118).

The spelling of 809919 in words is "eight hundred nine thousand, nine hundred nineteen".