9907840 has 64 divisors (see below), whose sum is σ = 24069960. Its totient is φ = 3899392.

The previous prime is 9907819. The next prime is 9907841. The reversal of 9907840 is 487099.

9907840 = 198² + 199² + ... + 334².

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 5345344 + 4562496 = 2312^2 + 2136^2 .

It is a tau number, because it is divible by the number of its divisors (64).

It is a self number, because there is not a number n which added to its sum of digits gives 9907840.

It is not an unprimeable number, because it can be changed into a prime (9907841) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 72252 + ... + 72388.

Almost surely, 2^9907840 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 9907840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12034980).

9907840 is an abundant number, since it is smaller than the sum of its proper divisors (14162120).

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

9907840 is a wasteful number, since it uses less digits than its factorization.

9907840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269 (or 257 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 37.

The square root of 9907840 is about 3147.6721557367. The cubic root of 9907840 is about 214.7795830125.

The spelling of 9907840 in words is "nine million, nine hundred seven thousand, eight hundred forty".