99999987 has 4 divisors (see below), whose sum is σ = 133333320. Its totient is φ = 66666656.

The previous prime is 99999971. The next prime is 99999989. The reversal of 99999987 is 78999999.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 99999987 - 2⁴ = 99999971 is a prime.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (99999989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16666662 + ... + 16666667.

It is an arithmetic number, because the mean of its divisors is an integer number (33333330).

Almost surely, 2^99999987 is an apocalyptic number.

99999987 is a deficient number, since it is larger than the sum of its proper divisors (33333333).

99999987 is a wasteful number, since it uses less digits than its factorization.

99999987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33333332.

The product of its digits is 29760696, while the sum is 69.

The square root of 99999987 is about 9999.9993500000. Note that the first 3 decimals coincide. The cubic root of 99999987 is about 464.1588632477.

The spelling of 99999987 in words is "ninety-nine million, nine hundred ninety-nine thousand, nine hundred eighty-seven".