561243542502221 has 4 divisors (see below), whose sum is σ = 561245525046492. Its totient is φ = 561241559957952.

The previous prime is 561243542502143. The next prime is 561243542502241. The reversal of 561243542502221 is 122205245342165.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 532456132650121 + 28787409852100 = 23075011^2 + 5365390^2 .

It is a cyclic number.

It is not a de Polignac number, because 561243542502221 - 2¹⁰ = 561243542501197 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 (561243542502241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 990847436 + ... + 991413701.

It is an arithmetic number, because the mean of its divisors is an integer number (140311381261623).

Almost surely, 2^{561243542502221} is an apocalyptic number.

It is an amenable number.

561243542502221 is a deficient number, since it is larger than the sum of its proper divisors (1982544271).

561243542502221 is a wasteful number, since it uses less digits than its factorization.

561243542502221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1982544270.

The product of its (nonzero) digits is 1152000, while the sum is 44.

Adding to 561243542502221 its reverse (122205245342165), we get a palindrome (683448787844386).

The spelling of 561243542502221 in words is "five hundred sixty-one trillion, two hundred forty-three billion, five hundred forty-two million, five hundred two thousand, two hundred twenty-one".