99811987 has 16 divisors (see below), whose sum is σ = 112717440. Its totient is φ = 87595200.

The previous prime is 99811979. The next prime is 99812023. The reversal of 99811987 is 78911899.

It is not a de Polignac number, because 99811987 - 2³ = 99811979 is a prime.

It is not an unprimeable number, because it can be changed into a prime (99811087) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40912 + ... + 43282.

It is an arithmetic number, because the mean of its divisors is an integer number (7044840).

Almost surely, 2^99811987 is an apocalyptic number.

99811987 is a deficient number, since it is larger than the sum of its proper divisors (12905453).

99811987 is a wasteful number, since it uses less digits than its factorization.

99811987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2514.

The product of its digits is 326592, while the sum is 52.

The square root of 99811987 is about 9990.5949272303. The cubic root of 99811987 is about 463.8678078513.

The spelling of 99811987 in words is "ninety-nine million, eight hundred eleven thousand, nine hundred eighty-seven".