999899 has 4 divisors (see below), whose sum is σ = 1003464. Its totient is φ = 996336.

The previous prime is 999883. The next prime is 999907. The reversal of 999899 is 998999.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 998999 = 179 ⋅5581.

It is a cyclic number.

It is not a de Polignac number, because 999899 - 2⁴ = 999883 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 999899.

It is not an unprimeable number, because it can be changed into a prime (999809) 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, 1322 + ... + 1935.

It is an arithmetic number, because the mean of its divisors is an integer number (250866).

2⁹⁹⁹⁸⁹⁹ is an apocalyptic number.

999899 is a deficient number, since it is larger than the sum of its proper divisors (3565).

999899 is a wasteful number, since it uses less digits than its factorization.

999899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3564.

The product of its digits is 472392, while the sum is 53.

The square root of 999899 is about 999.9494987248. The cubic root of 999899 is about 99.9966332200.

Subtracting from 999899 its reverse (998999), we obtain a square (900 = 30²).

The spelling of 999899 in words is "nine hundred ninety-nine thousand, eight hundred ninety-nine".