809990 has 16 divisors (see below), whose sum is σ = 1473552. Its totient is φ = 320544.

The previous prime is 809983. The next prime is 809993. The reversal of 809990 is 99908.

It is an Ulam number.

It is a plaindrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 809990.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (809993) by changing a digit.

809990 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 692 + ... + 1448.

It is an arithmetic number, because the mean of its divisors is an integer number (92097).

2⁸⁰⁹⁹⁹⁰ is an apocalyptic number.

809990 is a deficient number, since it is larger than the sum of its proper divisors (663562).

809990 is a wasteful number, since it uses less digits than its factorization.

809990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 871.

The product of its (nonzero) digits is 5832, while the sum is 35.

The square root of 809990 is about 899.9944444273. The cubic root of 809990 is about 93.2165915681.

The spelling of 809990 in words is "eight hundred nine thousand, nine hundred ninety".