820161 has 6 divisors (see below), whose sum is σ = 1184690. Its totient is φ = 546768.

The previous prime is 820133. The next prime is 820163. The reversal of 820161 is 161028.

It can be written as a sum of positive squares in only one way, i.e., 690561 + 129600 = 831^2 + 360^2 .

It is not a de Polignac number, because 820161 - 2⁵ = 820129 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (820163) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 45556 + ... + 45573.

2⁸²⁰¹⁶¹ is an apocalyptic number.

It is an amenable number.

820161 is a deficient number, since it is larger than the sum of its proper divisors (364529).

820161 is a wasteful number, since it uses less digits than its factorization.

820161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91135 (or 91132 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 820161 is about 905.6274068291. The cubic root of 820161 is about 93.6051416198.

Adding to 820161 its reverse (161028), we get a palindrome (981189).

The spelling of 820161 in words is "eight hundred twenty thousand, one hundred sixty-one".