165866820 has 96 divisors (see below), whose sum is σ = 537600000. Its totient is φ = 37425024.

The previous prime is 165866809. The next prime is 165866821. The reversal of 165866820 is 28668561.

165866820 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (165866821) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 30681 + ... + 35679.

It is an arithmetic number, because the mean of its divisors is an integer number (5600000).

Almost surely, 2^165866820 is an apocalyptic number.

165866820 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 165866820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (268800000).

165866820 is an abundant number, since it is smaller than the sum of its proper divisors (371733180).

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

165866820 is a wasteful number, since it uses less digits than its factorization.

165866820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5097 (or 5095 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 42.

The square root of 165866820 is about 12878.9293033233. The cubic root of 165866820 is about 549.4394509322.

The spelling of 165866820 in words is "one hundred sixty-five million, eight hundred sixty-six thousand, eight hundred twenty".