999555809280 has 240 divisors, whose sum is σ = 3655413121920. Its totient is φ = 228469506048.

The previous prime is 999555809279. The next prime is 999555809281. The reversal of 999555809280 is 82908555999.

It is an interprime number because it is at equal distance from previous prime (999555809279) and next prime (999555809281).

It is a tau number, because it is divible by the number of its divisors (240).

It is a super-2 number, since 2×999555809280² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999555809281) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1429806 + ... + 2010834.

It is an arithmetic number, because the mean of its divisors is an integer number (15230888008).

Almost surely, 2^999555809280 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 999555809280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1827706560960).

999555809280 is an abundant number, since it is smaller than the sum of its proper divisors (2655857312640).

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

999555809280 is an equidigital number, since it uses as much as digits as its factorization.

999555809280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 581072 (or 581046 counting only the distinct ones).

The product of its (nonzero) digits is 104976000, while the sum is 69.

The spelling of 999555809280 in words is "nine hundred ninety-nine billion, five hundred fifty-five million, eight hundred nine thousand, two hundred eighty".