999521851680 has 1152 divisors, whose sum is σ = 4113710012160. Its totient is φ = 224705249280.

The previous prime is 999521851637. The next prime is 999521851681. The reversal of 999521851680 is 86158125999.

999521851680 is a `hidden beast` number, since 9 + 9 + 95 + 21 + 8 + 516 + 8 + 0 = 666.

It is not an unprimeable number, because it can be changed into a prime (999521851681) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1002528942 + ... + 1002529938.

It is an arithmetic number, because the mean of its divisors is an integer number (3570928830).

Almost surely, 2^999521851680 is an apocalyptic number.

999521851680 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 999521851680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2056855006080).

999521851680 is an abundant number, since it is smaller than the sum of its proper divisors (3114188160480).

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

999521851680 is a wasteful number, since it uses less digits than its factorization.

999521851680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1139 (or 1108 counting only the distinct ones).

The product of its (nonzero) digits is 13996800, while the sum is 63.

The spelling of 999521851680 in words is "nine hundred ninety-nine billion, five hundred twenty-one million, eight hundred fifty-one thousand, six hundred eighty".