561639 has 8 divisors (see below), whose sum is σ = 806512. Its totient is φ = 345600.

The previous prime is 561607. The next prime is 561667. The reversal of 561639 is 936165.

It is a happy number.

561639 is digitally balanced in base 2 and base 7, because in such bases it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 561639 - 2⁵ = 561607 is a prime.

It is a Duffinian number.

561639 is strictly pandigital in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561439) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7162 + ... + 7239.

It is an arithmetic number, because the mean of its divisors is an integer number (100814).

2⁵⁶¹⁶³⁹ is an apocalyptic number.

561639 is a deficient number, since it is larger than the sum of its proper divisors (244873).

561639 is a wasteful number, since it uses less digits than its factorization.

561639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14417.

The product of its digits is 4860, while the sum is 30.

The square root of 561639 is about 749.4257801811. The cubic root of 561639 is about 82.5060417981.

It can be divided in two parts, 5616 and 39, that multiplied together give a square (219024 = 468²).

The spelling of 561639 in words is "five hundred sixty-one thousand, six hundred thirty-nine".