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BaseRepresentation
bin1011111010111…
…10000011111111
320222011112012200
411331132003333
5201044444444
613531202543
72322662121
oct575360377
9228145180
1099999999
11514a1530
12295a6453
13179437c8
14d3d1211
158ba4969
hex5f5e0ff

99999999 has 48 divisors (see below), whose sum is σ = 162493344. Its totient is φ = 58752000.

The previous prime is 99999989. The next prime is 100000007.

99999999 is nontrivially palindromic in base 10.

It is a Cunningham number, because it is equal to 108-1.

It is a trimorphic number since its cube, 999999970000000299999999, ends in 99999999.

It is not a de Polignac number, because 99999999 - 216 = 99934463 is a prime.

It is a nude number because it is divisible by every one of its digits.

99999999 is a modest number, since divided by 99999 gives 999 as remainder.

99999999 is a nontrivial repdigit in base 10.

It is a plaindrome in base 10.

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 (99999959) by changing a digit.

It is a Kaprekar number, because its square (9999999800000001) can be partitioned into two parts whose sum is 99999999.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 729859 + ... + 729995.

It is an arithmetic number, because the mean of its divisors is an integer number (3385278).

Almost surely, 299999999 is an apocalyptic number.

99999999 is a gapful number since it is divisible by the number (99) formed by its first and last digit.

99999999 is a deficient number, since it is larger than the sum of its proper divisors (62493345).

99999999 is a wasteful number, since it uses less digits than its factorization.

99999999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328 (or 325 counting only the distinct ones).

The product of its digits is 43046721, while the sum is 72.

The square root of 99999999 is about 9999.9999500000. Note that the first 4 decimals coincide. The cubic root of 99999999 is about 464.1588818141.

The spelling of 99999999 in words is "ninety-nine million, nine hundred ninety-nine thousand, nine hundred ninety-nine".