165421800 has 144 divisors (see below), whose sum is σ = 574879500. Its totient is φ = 42577920.

The previous prime is 165421799. The next prime is 165421807. The reversal of 165421800 is 8124561.

165421800 is a `hidden beast` number, since 1 + 654 + 2 + 1 + 8 + 0 + 0 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 90668484 + 74753316 = 9522^2 + 8646^2 .

It is not an unprimeable number, because it can be changed into a prime (165421807) 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 35 ways as a sum of consecutive naturals, for example, 50616 + ... + 53784.

Almost surely, 2^165421800 is an apocalyptic number.

165421800 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 165421800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (287439750).

165421800 is an abundant number, since it is smaller than the sum of its proper divisors (409457700).

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

165421800 is a wasteful number, since it uses less digits than its factorization.

165421800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3220 (or 3208 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 165421800 is about 12861.6406418466. The cubic root of 165421800 is about 548.9476295511.

The spelling of 165421800 in words is "one hundred sixty-five million, four hundred twenty-one thousand, eight hundred".