99999988 has 12 divisors (see below), whose sum is σ = 190909152.
Its totient is φ = 45454520.
The previous prime is 99999971. The next prime is 99999989. The reversal of 99999988 is 88999999.
It is a nialpdrome in base 10.
It is a zygodrome in base 10.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (99999989) 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, 1136320 + ... + 1136407.
It is an arithmetic number, because the mean of its divisors is an integer number (15909096).
Almost surely, 299999988 is an apocalyptic number.
It is an amenable number.
99999988 is a deficient number, since it is larger than the sum of its proper divisors (90909164).
99999988 is a wasteful number, since it uses less digits than its factorization.
99999988 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 2272742 (or 2272740 counting only the distinct ones).
The product of its digits is 34012224, while the sum is 70.
The square root of 99999988 is about 9999.9994000000.
Note that the first 3 decimals coincide.
The cubic root of 99999988 is about 464.1588647949.
The spelling of 99999988 in words is "ninety-nine million, nine hundred ninety-nine thousand, nine hundred eighty-eight".