561691764 has 72 divisors (see below), whose sum is σ = 1506927240. Its totient is φ = 175798272.

The previous prime is 561691733. The next prime is 561691769. The reversal of 561691764 is 467196165.

It can be written as a sum of positive squares in 4 ways, for example, as 93315600 + 468376164 = 9660^2 + 21642^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561691769) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 347422 + ... + 349034.

It is an arithmetic number, because the mean of its divisors is an integer number (20929545).

Almost surely, 2^561691764 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 561691764, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (753463620).

561691764 is an abundant number, since it is smaller than the sum of its proper divisors (945235476).

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

561691764 is a wasteful number, since it uses less digits than its factorization.

561691764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2209 (or 2204 counting only the distinct ones).

The product of its digits is 272160, while the sum is 45.

The square root of 561691764 is about 23700.0372151607. The cubic root of 561691764 is about 825.0862543426.

It can be divided in two parts, 561691 and 764, that multiplied together give a palindrome (429131924).

The spelling of 561691764 in words is "five hundred sixty-one million, six hundred ninety-one thousand, seven hundred sixty-four".