9905235017821 has 16 divisors (see below), whose sum is σ = 11639750830848. Its totient is φ = 8310062923200.

The previous prime is 9905235017813. The next prime is 9905235017891. The reversal of 9905235017821 is 1287105325099.

It is a cyclic number.

It is not a de Polignac number, because 9905235017821 - 2³ = 9905235017813 is a prime.

It is a super-2 number, since 2×9905235017821² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9905235017891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7836766 + ... + 9012511.

It is an arithmetic number, because the mean of its divisors is an integer number (727484426928).

Almost surely, 2^{9905235017821} is an apocalyptic number.

It is an amenable number.

9905235017821 is a deficient number, since it is larger than the sum of its proper divisors (1734515813027).

9905235017821 is a wasteful number, since it uses less digits than its factorization.

9905235017821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16853412.

The product of its (nonzero) digits is 1360800, while the sum is 52.

The spelling of 9905235017821 in words is "nine trillion, nine hundred five billion, two hundred thirty-five million, seventeen thousand, eight hundred twenty-one".