561720 has 64 divisors (see below), whose sum is σ = 1751040. Its totient is φ = 144000.

The previous prime is 561713. The next prime is 561733. The reversal of 561720 is 27165.

It is a hoax number, since the sum of its digits (21) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3645 + ... + 3795.

It is an arithmetic number, because the mean of its divisors is an integer number (27360).

2⁵⁶¹⁷²⁰ 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 561720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (875520).

561720 is an abundant number, since it is smaller than the sum of its proper divisors (1189320).

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

561720 is a wasteful number, since it uses less digits than its factorization.

561720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196 (or 192 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 561720 is about 749.4798196082. The cubic root of 561720 is about 82.5100079686.

Adding to 561720 its reverse (27165), we get a palindrome (588885).

The spelling of 561720 in words is "five hundred sixty-one thousand, seven hundred twenty".