561547661 has 4 divisors (see below), whose sum is σ = 561894432. Its totient is φ = 561200892.

The previous prime is 561547643. The next prime is 561547669. The reversal of 561547661 is 166745165.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 166745165 = 5 ⋅33349033.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-561547661 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 (561547669) 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, 170945 + ... + 174198.

It is an arithmetic number, because the mean of its divisors is an integer number (140473608).

Almost surely, 2^561547661 is an apocalyptic number.

It is an amenable number.

561547661 is a deficient number, since it is larger than the sum of its proper divisors (346771).

561547661 is a wasteful number, since it uses less digits than its factorization.

561547661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 346770.

The product of its digits is 151200, while the sum is 41.

The square root of 561547661 is about 23696.9968772416. The cubic root of 561547661 is about 825.0156892027.

The spelling of 561547661 in words is "five hundred sixty-one million, five hundred forty-seven thousand, six hundred sixty-one".