99891987 has 16 divisors (see below), whose sum is σ = 150984960. Its totient is φ = 58236192.

The previous prime is 99891947. The next prime is 99891989. The reversal of 99891987 is 78919899.

It is not a de Polignac number, because 99891987 - 2⁶ = 99891923 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 99891987.

It is not an unprimeable number, because it can be changed into a prime (99891989) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66663 + ... + 68144.

It is an arithmetic number, because the mean of its divisors is an integer number (9436560).

Almost surely, 2^99891987 is an apocalyptic number.

99891987 is a deficient number, since it is larger than the sum of its proper divisors (51092973).

99891987 is a wasteful number, since it uses less digits than its factorization.

99891987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134842.

The product of its digits is 2939328, while the sum is 60.

The square root of 99891987 is about 9994.5978908608. The cubic root of 99891987 is about 463.9917058441.

The spelling of 99891987 in words is "ninety-nine million, eight hundred ninety-one thousand, nine hundred eighty-seven".