165601620 has 72 divisors (see below), whose sum is σ = 507354120. Its totient is φ = 43718400.

The previous prime is 165601609. The next prime is 165601621. The reversal of 165601620 is 26106561.

It is a happy number.

165601620 is a `hidden beast` number, since 1 + 656 + 0 + 1 + 6 + 2 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 24324624 + 141276996 = 4932^2 + 11886^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165601621) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13626 + ... + 22734.

It is an arithmetic number, because the mean of its divisors is an integer number (7046585).

Almost surely, 2^165601620 is an apocalyptic number.

165601620 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 165601620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (253677060).

165601620 is an abundant number, since it is smaller than the sum of its proper divisors (341752500).

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

165601620 is a wasteful number, since it uses less digits than its factorization.

165601620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9225 (or 9220 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 165601620 is about 12868.6292976369. The cubic root of 165601620 is about 549.1464667388.

The spelling of 165601620 in words is "one hundred sixty-five million, six hundred one thousand, six hundred twenty".