99840640 has 64 divisors (see below), whose sum is σ = 242064360. Its totient is φ = 39370752.

The previous prime is 99840623. The next prime is 99840647. The reversal of 99840640 is 4604899.

It can be written as a sum of positive squares in 4 ways, for example, as 56911936 + 42928704 = 7544^2 + 6552^2 .

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

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 99840593 and 99840602.

It is not an unprimeable number, because it can be changed into a prime (99840647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45652 + ... + 47788.

Almost surely, 2^99840640 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 99840640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121032180).

99840640 is an abundant number, since it is smaller than the sum of its proper divisors (142223720).

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

99840640 is a wasteful number, since it uses less digits than its factorization.

99840640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2229 (or 2217 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 40.

The square root of 99840640 is about 9992.0288230169. The cubic root of 99840640 is about 463.9121910730.

The spelling of 99840640 in words is "ninety-nine million, eight hundred forty thousand, six hundred forty".