561661604 has 12 divisors (see below), whose sum is σ = 1123323264. Its totient is φ = 240712104.

The previous prime is 561661601. The next prime is 561661619. The reversal of 561661604 is 406166165.

561661604 is an admirable number.

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (561661601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10029644 + ... + 10029699.

It is an arithmetic number, because the mean of its divisors is an integer number (93610272).

Almost surely, 2^561661604 is an apocalyptic number.

It is an amenable number.

561661604 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

561661604 is a wasteful number, since it uses less digits than its factorization.

561661604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20059354 (or 20059352 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 561661604 is about 23699.4009206984. The cubic root of 561661604 is about 825.0714864287.

It can be divided in two parts, 561661 and 604, that added together give a palindrome (562265).

The spelling of 561661604 in words is "five hundred sixty-one million, six hundred sixty-one thousand, six hundred four".