561640 has 32 divisors (see below), whose sum is σ = 1332000. Its totient is φ = 212544.

The previous prime is 561607. The next prime is 561667. The reversal of 561640 is 46165.

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, 391 + ... + 1129.

It is an arithmetic number, because the mean of its divisors is an integer number (41625).

2⁵⁶¹⁶⁴⁰ 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 561640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (666000).

561640 is an abundant number, since it is smaller than the sum of its proper divisors (770360).

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

561640 is a wasteful number, since it uses less digits than its factorization.

561640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 769 (or 765 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 561640 is about 749.4264473582. The cubic root of 561640 is about 82.5060907655.

The spelling of 561640 in words is "five hundred sixty-one thousand, six hundred forty".