9905906443225 has 81 divisors (see below), whose sum is σ = 13644755132997. Its totient is φ = 7130670144000.

The previous prime is 9905906443207. The next prime is 9905906443231. The reversal of 9905906443225 is 5223446095099.

The square root of 9905906443225 is 3147365.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 40 ways, for example, as 6717981896649 + 3187924546576 = 2591907^2 + 1785476^2 .

It is not a de Polignac number, because 9905906443225 - 2²⁷ = 9905772225497 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 9905906443225.

It is an unprimeable number.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 8387727135 + ... + 8387728315.

Almost surely, 2^{9905906443225} is an apocalyptic number.

9905906443225 is the 3147365-th square number.

9905906443225 is the 1573683-rd centered octagonal number.

It is an amenable number.

9905906443225 is a deficient number, since it is larger than the sum of its proper divisors (3738848689772).

9905906443225 is an equidigital number, since it uses as much as digits as its factorization.

9905906443225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2480 (or 1240 counting only the distinct ones).

The product of its (nonzero) digits is 20995200, while the sum is 58.

The spelling of 9905906443225 in words is "nine trillion, nine hundred five billion, nine hundred six million, four hundred forty-three thousand, two hundred twenty-five".