99987665 has 4 divisors (see below), whose sum is σ = 119985204. Its totient is φ = 79990128.

The previous prime is 99987619. The next prime is 99987683. The reversal of 99987665 is 56678999.

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

It can be written as a sum of positive squares in 2 ways, for example, as 51782416 + 48205249 = 7196^2 + 6943^2 .

It is a cyclic number.

It is not a de Polignac number, because 99987665 - 2¹⁰ = 99986641 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a nialpdrome in base 10.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9998762 + ... + 9998771.

It is an arithmetic number, because the mean of its divisors is an integer number (29996301).

Almost surely, 2^99987665 is an apocalyptic number.

It is an amenable number.

99987665 is a deficient number, since it is larger than the sum of its proper divisors (19997539).

99987665 is a wasteful number, since it uses less digits than its factorization.

99987665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19997538.

The product of its digits is 7348320, while the sum is 59.

The square root of 99987665 is about 9999.3832309798. The cubic root of 99987665 is about 464.1397979104.

The spelling of 99987665 in words is "ninety-nine million, nine hundred eighty-seven thousand, six hundred sixty-five".