99979999 has 8 divisors (see below), whose sum is σ = 115872768.
Its totient is φ = 84489720.
The previous prime is 99979993. The next prime is 99980003. The reversal of 99979999 is 99997999.
It is a sphenic number, since it is the product of 3 distinct primes.
It is not a de Polignac number, because 99979999 - 25 = 99979967 is a prime.
It is a Duffinian number.
99979999 is a modest number, since divided by 9999 gives 9997 as remainder.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (99979993) 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, 100087 + ... + 101080.
It is an arithmetic number, because the mean of its divisors is an integer number (14484096).
Almost surely, 299979999 is an apocalyptic number.
99979999 is a deficient number, since it is larger than the sum of its proper divisors (15892769).
99979999 is a wasteful number, since it uses less digits than its factorization.
99979999 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 201245.
The product of its digits is 33480783, while the sum is 70.
The square root of 99979999 is about 9998.9998999900.
Note that the first 3 decimals coincide.
The cubic root of 99979999 is about 464.1279358252.
The spelling of 99979999 in words is "ninety-nine million, nine hundred seventy-nine thousand, nine hundred ninety-nine".