997809 has 8 divisors (see below), whose sum is σ = 1388352. Its totient is φ = 636240.

The previous prime is 997807. The next prime is 997811. The reversal of 997809 is 908799.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (997807) and next prime (997811).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 997809 - 2¹ = 997807 is a prime.

997809 is a lucky number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 997809.

It is not an unprimeable number, because it can be changed into a prime (997807) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7162 + ... + 7299.

It is an arithmetic number, because the mean of its divisors is an integer number (173544).

2⁹⁹⁷⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

997809 is a deficient number, since it is larger than the sum of its proper divisors (390543).

997809 is a wasteful number, since it uses less digits than its factorization.

997809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14487.

The product of its (nonzero) digits is 40824, while the sum is 42.

The square root of 997809 is about 998.9038992816. The cubic root of 997809 is about 99.9269132630.

The spelling of 997809 in words is "nine hundred ninety-seven thousand, eight hundred nine".