9905819521 has 16 divisors (see below), whose sum is σ = 10781765568. Its totient is φ = 9046296000.

The previous prime is 9905819503. The next prime is 9905819531. The reversal of 9905819521 is 1259185099.

It is a cyclic number.

It is not a de Polignac number, because 9905819521 - 2⁵ = 9905819489 is a prime.

It is a super-3 number, since 3×9905819521³ (a number of 31 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9905819531) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2533450 + ... + 2537356.

It is an arithmetic number, because the mean of its divisors is an integer number (673860348).

Almost surely, 2^9905819521 is an apocalyptic number.

It is an amenable number.

9905819521 is a deficient number, since it is larger than the sum of its proper divisors (875946047).

9905819521 is a wasteful number, since it uses less digits than its factorization.

9905819521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5952.

The product of its (nonzero) digits is 291600, while the sum is 49.

The square root of 9905819521 is about 99527.9836076267. The cubic root of 9905819521 is about 2147.6498221355.

The spelling of 9905819521 in words is "nine billion, nine hundred five million, eight hundred nineteen thousand, five hundred twenty-one".