999643680 has 288 divisors, whose sum is σ = 4044104064. Its totient is φ = 228427776.

The previous prime is 999643669. The next prime is 999643681. The reversal of 999643680 is 86346999.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (999643681) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 270324 + ... + 273996.

It is an arithmetic number, because the mean of its divisors is an integer number (14042028).

Almost surely, 2^999643680 is an apocalyptic number.

999643680 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 999643680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2022052032).

999643680 is an abundant number, since it is smaller than the sum of its proper divisors (3044460384).

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

999643680 is a wasteful number, since it uses less digits than its factorization.

999643680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3710 (or 3690 counting only the distinct ones).

The product of its (nonzero) digits is 2519424, while the sum is 54.

The square root of 999643680 is about 31617.1421858460. The cubic root of 999643680 is about 999.8812125568.

The spelling of 999643680 in words is "nine hundred ninety-nine million, six hundred forty-three thousand, six hundred eighty".