165821428800 has 336 divisors, whose sum is σ = 605989339200. Its totient is φ = 44108697600.

The previous prime is 165821428793. The next prime is 165821428831. The reversal of 165821428800 is 8824128561.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 18096220 + ... + 18105380.

It is an arithmetic number, because the mean of its divisors is an integer number (1803539700).

Almost surely, 2^165821428800 is an apocalyptic number.

165821428800 is a gapful number since it is divisible by the number (10) 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 165821428800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (302994669600).

165821428800 is an abundant number, since it is smaller than the sum of its proper divisors (440167910400).

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

165821428800 is a wasteful number, since it uses less digits than its factorization.

165821428800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9611 (or 9590 counting only the distinct ones).

The product of its (nonzero) digits is 245760, while the sum is 45.

The spelling of 165821428800 in words is "one hundred sixty-five billion, eight hundred twenty-one million, four hundred twenty-eight thousand, eight hundred".