999980 has 12 divisors (see below), whose sum is σ = 2100000. Its totient is φ = 399984.

The previous prime is 999979. The next prime is 999983. The reversal of 999980 is 89999.

It is an Ulam number.

It is a nialpdrome in base 10.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 999980.

It is not an unprimeable number, because it can be changed into a prime (999983) 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, 24980 + ... + 25019.

It is an arithmetic number, because the mean of its divisors is an integer number (175000).

2⁹⁹⁹⁹⁸⁰ is an apocalyptic number.

It is an amenable number.

999980 is an abundant number, since it is smaller than the sum of its proper divisors (1100020).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

999980 is a wasteful number, since it uses less digits than its factorization.

999980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50008 (or 50006 counting only the distinct ones).

The product of its (nonzero) digits is 52488, while the sum is 44.

The square root of 999980 is about 999.9899999500. The cubic root of 999980 is about 99.9993333289. Note that the first 3 decimals are identical.

The spelling of 999980 in words is "nine hundred ninety-nine thousand, nine hundred eighty".