561865 has 8 divisors (see below), whose sum is σ = 681408. Its totient is φ = 444720.

The previous prime is 561839. The next prime is 561907. The reversal of 561865 is 568165.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 561865 - 2¹⁵ = 529097 is a prime.

It is a Duffinian number.

561865 is a lucky number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31 + ... + 1060.

It is an arithmetic number, because the mean of its divisors is an integer number (85176).

2⁵⁶¹⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

561865 is a deficient number, since it is larger than the sum of its proper divisors (119543).

561865 is a wasteful number, since it uses less digits than its factorization.

561865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1199.

The product of its digits is 7200, while the sum is 31.

The square root of 561865 is about 749.5765471251. The cubic root of 561865 is about 82.5171069514.

The spelling of 561865 in words is "five hundred sixty-one thousand, eight hundred sixty-five".