66820 has 24 divisors (see below), whose sum is σ = 151704. Its totient is φ = 24576.

The previous prime is 66809. The next prime is 66821. The reversal of 66820 is 2866.

It can be written as a sum of positive squares in 4 ways, for example, as 12996 + 53824 = 114^2 + 232^2 .

It is a junction number, because it is equal to n+sod(n) for n = 66791 and 66800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 132 + ... + 388.

It is an arithmetic number, because the mean of its divisors is an integer number (6321).

2⁶⁶⁸²⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (75852).

66820 is an abundant number, since it is smaller than the sum of its proper divisors (84884).

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

66820 is a wasteful number, since it uses less digits than its factorization.

66820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279 (or 277 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 66820 is about 258.4956479324. The cubic root of 66820 is about 40.5790763112.

The spelling of 66820 in words is "sixty-six thousand, eight hundred twenty".