561817 has 4 divisors (see below), whose sum is σ = 581220. Its totient is φ = 542416.

The previous prime is 561809. The next prime is 561829. The reversal of 561817 is 718165.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 226576 + 335241 = 476^2 + 579^2 .

It is not a de Polignac number, because 561817 - 2³ = 561809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (561917) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9658 + ... + 9715.

It is an arithmetic number, because the mean of its divisors is an integer number (145305).

2⁵⁶¹⁸¹⁷ is an apocalyptic number.

It is an amenable number.

561817 is a deficient number, since it is larger than the sum of its proper divisors (19403).

561817 is a wasteful number, since it uses less digits than its factorization.

561817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19402.

The product of its digits is 1680, while the sum is 28.

The square root of 561817 is about 749.5445283637. The cubic root of 561817 is about 82.5147570786.

It can be divided in two parts, 561 and 817, that added together give a triangular number (1378 = T₅₂).

The spelling of 561817 in words is "five hundred sixty-one thousand, eight hundred seventeen".