9721845 has 36 divisors (see below), whose sum is σ = 19606860. Its totient is φ = 4443264.

The previous prime is 9721837. The next prime is 9721849. The reversal of 9721845 is 5481279.

9721845 is a nontrivial binomial coefficient, being equal to C(4410, 2).

It can be written as a sum of positive squares in 2 ways, for example, as 1920996 + 7800849 = 1386^2 + 2793^2 .

It is not a de Polignac number, because 9721845 - 2³ = 9721837 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9721849) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1 + ... + 4409.

It is an arithmetic number, because the mean of its divisors is an integer number (544635).

Almost surely, 2^9721845 is an apocalyptic number.

9721845 is the 4409-th triangular number and also the 2205-th hexagonal number.

It is an amenable number.

9721845 is an abundant number, since it is smaller than the sum of its proper divisors (9885015).

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

9721845 is a wasteful number, since it uses less digits than its factorization.

9721845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4434 (or 4424 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 9721845 is about 3117.9873315971. The cubic root of 9721845 is about 213.4271004360.

The spelling of 9721845 in words is "nine million, seven hundred twenty-one thousand, eight hundred forty-five".