99987 has 4 divisors (see below), whose sum is σ = 133320. Its totient is φ = 66656.

The previous prime is 99971. The next prime is 99989. The reversal of 99987 is 78999.

It is a happy number.

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 99987 - 2⁴ = 99971 is a prime.

It is a D-number.

99987 is a lucky number.

It is a nialpdrome in base 10.

It is a zygodrome in base 5.

It is not an unprimeable number, because it can be changed into a prime (99989) 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, 16662 + ... + 16667.

It is an arithmetic number, because the mean of its divisors is an integer number (33330).

2⁹⁹⁹⁸⁷ is an apocalyptic number.

99987 is a deficient number, since it is larger than the sum of its proper divisors (33333).

99987 is a wasteful number, since it uses less digits than its factorization.

99987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33332.

The product of its digits is 40824, while the sum is 42.

The square root of 99987 is about 316.2072105440. The cubic root of 99987 is about 46.4138768938.

The spelling of 99987 in words is "ninety-nine thousand, nine hundred eighty-seven".