561820 has 24 divisors (see below), whose sum is σ = 1348704. Its totient is φ = 192576.

The previous prime is 561809. The next prime is 561829. The reversal of 561820 is 28165.

It is a happy number.

It is a hoax number, since the sum of its digits (22) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 561791 and 561800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561829) 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, 1867 + ... + 2146.

It is an arithmetic number, because the mean of its divisors is an integer number (56196).

2⁵⁶¹⁸²⁰ is an apocalyptic number.

It is an amenable number.

561820 is an abundant number, since it is smaller than the sum of its proper divisors (786884).

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

561820 is a wasteful number, since it uses less digits than its factorization.

561820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4029 (or 4027 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 561820 is about 749.5465295764. The cubic root of 561820 is about 82.5149039496.

Adding to 561820 its reverse (28165), we get a palindrome (589985).

The spelling of 561820 in words is "five hundred sixty-one thousand, eight hundred twenty".