9721440 has 144 divisors (see below), whose sum is σ = 34162128. Its totient is φ = 2515968.

The previous prime is 9721429. The next prime is 9721441. The reversal of 9721440 is 441279.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (144).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9721441) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 61842 + ... + 61998.

It is an arithmetic number, because the mean of its divisors is an integer number (237237).

Almost surely, 2^9721440 is an apocalyptic number.

9721440 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9721440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17081064).

9721440 is an abundant number, since it is smaller than the sum of its proper divisors (24440688).

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

9721440 is a wasteful number, since it uses less digits than its factorization.

9721440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221 (or 210 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 9721440 is about 3117.9223851790. The cubic root of 9721440 is about 213.4241366921.

The spelling of 9721440 in words is "nine million, seven hundred twenty-one thousand, four hundred forty".