561391 has 4 divisors (see below), whose sum is σ = 594432. Its totient is φ = 528352.

The previous prime is 561389. The next prime is 561409. The reversal of 561391 is 193165.

561391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 561391 - 2¹ = 561389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561091) 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, 16495 + ... + 16528.

It is an arithmetic number, because the mean of its divisors is an integer number (148608).

2⁵⁶¹³⁹¹ is an apocalyptic number.

561391 is a deficient number, since it is larger than the sum of its proper divisors (33041).

561391 is a wasteful number, since it uses less digits than its factorization.

561391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33040.

The product of its digits is 810, while the sum is 25.

The square root of 561391 is about 749.2603018978. The cubic root of 561391 is about 82.4938960896.

The spelling of 561391 in words is "five hundred sixty-one thousand, three hundred ninety-one".