561217981 has 2 divisors, whose sum is σ = 561217982. Its totient is φ = 561217980.

The previous prime is 561217973. The next prime is 561217999. The reversal of 561217981 is 189712165.

It is a happy number.

561217981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 446941881 + 114276100 = 21141^2 + 10690^2 .

It is a cyclic number.

It is not a de Polignac number, because 561217981 - 2³ = 561217973 is a prime.

It is a super-2 number, since 2×561217981² = 629931244395432722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (561217931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280608990 + 280608991.

It is an arithmetic number, because the mean of its divisors is an integer number (280608991).

Almost surely, 2^561217981 is an apocalyptic number.

It is an amenable number.

561217981 is a deficient number, since it is larger than the sum of its proper divisors (1).

561217981 is an equidigital number, since it uses as much as digits as its factorization.

561217981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 40.

The square root of 561217981 is about 23690.0397002622. The cubic root of 561217981 is about 824.8542042944.

The spelling of 561217981 in words is "five hundred sixty-one million, two hundred seventeen thousand, nine hundred eighty-one".