99987905 has 4 divisors (see below), whose sum is σ = 119985492. Its totient is φ = 79990320.

The previous prime is 99987893. The next prime is 99987907. The reversal of 99987905 is 50978999.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50978999 = 157 ⋅324707.

It can be written as a sum of positive squares in 2 ways, for example, as 25321024 + 74666881 = 5032^2 + 8641^2 .

It is not a de Polignac number, because 99987905 - 2¹⁰ = 99986881 is a prime.

It is a super-2 number, since 2×99987905² = 19995162292578050, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99987907) 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, 9998786 + ... + 9998795.

It is an arithmetic number, because the mean of its divisors is an integer number (29996373).

Almost surely, 2^99987905 is an apocalyptic number.

It is an amenable number.

99987905 is a deficient number, since it is larger than the sum of its proper divisors (19997587).

99987905 is a wasteful number, since it uses less digits than its factorization.

99987905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19997586.

The product of its (nonzero) digits is 1837080, while the sum is 56.

The square root of 99987905 is about 9999.3952317128. The cubic root of 99987905 is about 464.1401692678.

The spelling of 99987905 in words is "ninety-nine million, nine hundred eighty-seven thousand, nine hundred five".