9905840 has 120 divisors (see below), whose sum is σ = 28346400. Its totient is φ = 3217536.

The previous prime is 9905839. The next prime is 9905869. The reversal of 9905840 is 485099.

It is a super-2 number, since 2×9905840² = 196251332211200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 9905840.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 521351 + ... + 521369.

It is an arithmetic number, because the mean of its divisors is an integer number (236220).

Almost surely, 2^9905840 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9905840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14173200).

9905840 is an abundant number, since it is smaller than the sum of its proper divisors (18440560).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9905840 is a wasteful number, since it uses less digits than its factorization.

9905840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72 (or 33 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 35.

The square root of 9905840 is about 3147.3544446090. The cubic root of 9905840 is about 214.7651302130.

Multiplying 9905840 by its sum of digits (35), we get a square (346704400 = 18620²).

9905840 divided by its sum of digits (35) gives a square (283024 = 532²).

The spelling of 9905840 in words is "nine million, nine hundred five thousand, eight hundred forty".