20216233561 has 2 divisors, whose sum is σ = 20216233562. Its totient is φ = 20216233560.

The previous prime is 20216233559. The next prime is 20216233573. The reversal of 20216233561 is 16533261202.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13485015625 + 6731217936 = 116125^2 + 82044^2 .

It is a cyclic number.

It is not a de Polignac number, because 20216233561 - 2¹ = 20216233559 is a prime.

Together with 20216233559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20216233501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10108116780 + 10108116781.

It is an arithmetic number, because the mean of its divisors is an integer number (10108116781).

Almost surely, 2^20216233561 is an apocalyptic number.

It is an amenable number.

20216233561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20216233561 is an equidigital number, since it uses as much as digits as its factorization.

20216233561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12960, while the sum is 31.

Adding to 20216233561 its reverse (16533261202), we get a palindrome (36749494763).

The spelling of 20216233561 in words is "twenty billion, two hundred sixteen million, two hundred thirty-three thousand, five hundred sixty-one".