561133721 has 2 divisors, whose sum is σ = 561133722. Its totient is φ = 561133720.

The previous prime is 561133681. The next prime is 561133723. The reversal of 561133721 is 127331165.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 466344025 + 94789696 = 21595^2 + 9736^2 .

It is a cyclic number.

It is not a de Polignac number, because 561133721 - 2¹⁰ = 561132697 is a prime.

Together with 561133723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (561133723) 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 as a sum of consecutive naturals, namely, 280566860 + 280566861.

It is an arithmetic number, because the mean of its divisors is an integer number (280566861).

Almost surely, 2^561133721 is an apocalyptic number.

It is an amenable number.

561133721 is a deficient number, since it is larger than the sum of its proper divisors (1).

561133721 is an equidigital number, since it uses as much as digits as its factorization.

561133721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3780, while the sum is 29.

The square root of 561133721 is about 23688.2612489815. The cubic root of 561133721 is about 824.8129216459.

Adding to 561133721 its reverse (127331165), we get a palindrome (688464886).

The spelling of 561133721 in words is "five hundred sixty-one million, one hundred thirty-three thousand, seven hundred twenty-one".