998999 has 4 divisors (see below), whose sum is σ = 1004760. Its totient is φ = 993240.

The previous prime is 998989. The next prime is 999007. The reversal of 998999 is 999899.

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: 999899 = 307 ⋅3257.

It is a cyclic number.

It is not a de Polignac number, because 998999 - 2⁴ = 998983 is a prime.

It is a Duffinian number.

998999 is a modest number, since divided by 999 gives 998 as remainder.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 998999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (998909) 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, 2612 + ... + 2969.

It is an arithmetic number, because the mean of its divisors is an integer number (251190).

2⁹⁹⁸⁹⁹⁹ is an apocalyptic number.

998999 is a deficient number, since it is larger than the sum of its proper divisors (5761).

998999 is a wasteful number, since it uses less digits than its factorization.

998999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5760.

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

The square root of 998999 is about 999.4993746871. The cubic root of 998999 is about 99.9666221938.

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

The spelling of 998999 in words is "nine hundred ninety-eight thousand, nine hundred ninety-nine".