9905905 has 4 divisors (see below), whose sum is σ = 11887092. Its totient is φ = 7924720.

The previous prime is 9905891. The next prime is 9905911. The reversal of 9905905 is 5095099.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5095099 = 263 ⋅19373.

It can be written as a sum of positive squares in 2 ways, for example, as 1238769 + 8667136 = 1113^2 + 2944^2 .

It is not a de Polignac number, because 9905905 - 2¹¹ = 9903857 is a prime.

It is an Ulam number.

It is a Duffinian number.

9905905 is a lucky number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 990586 + ... + 990595.

It is an arithmetic number, because the mean of its divisors is an integer number (2971773).

Almost surely, 2^9905905 is an apocalyptic number.

It is an amenable number.

9905905 is a deficient number, since it is larger than the sum of its proper divisors (1981187).

9905905 is a wasteful number, since it uses less digits than its factorization.

9905905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1981186.

The product of its (nonzero) digits is 18225, while the sum is 37.

The square root of 9905905 is about 3147.3647707249. The cubic root of 9905905 is about 214.7655999596.

The spelling of 9905905 in words is "nine million, nine hundred five thousand, nine hundred five".