99999 has 12 divisors (see below), whose sum is σ = 148512.
Its totient is φ = 64800.
The previous prime is 99991. The next prime is 100003.
99999 is nontrivially palindromic in base 10.
It is a Cunningham number, because it is equal to 105-1.
It is a trimorphic number since its cube, 999970000299999, ends in 99999.
It is not a de Polignac number, because 99999 - 23 = 99991 is a prime.
It is a nude number because it is divisible by every one of its digits.
99999 is a modest number, since divided by 999 gives 99 as remainder.
99999 is a nontrivial repdigit in base 10.
It is a plaindrome in base 5 and base 10.
It is a nialpdrome in base 10.
It is a zygodrome in base 5 and base 10.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (99991) by changing a digit.
It is a Kaprekar number, because its square (9999800001) can be partitioned into two parts whose sum is 99999.
It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 234 + ... + 504.
It is an arithmetic number, because the mean of its divisors is an integer number (12376).
299999 is an apocalyptic number.
99999 is a deficient number, since it is larger than the sum of its proper divisors (48513).
99999 is a wasteful number, since it uses less digits than its factorization.
99999 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 318 (or 315 counting only the distinct ones).
The product of its digits is 59049, while the sum is 45.
The square root of 99999 is about 316.2261848741.
The cubic root of 99999 is about 46.4157336160.
The spelling of 99999 in words is "ninety-nine thousand, nine hundred ninety-nine".