20230021561 has 2 divisors, whose sum is σ = 20230021562. Its totient is φ = 20230021560.

The previous prime is 20230021547. The next prime is 20230021597. The reversal of 20230021561 is 16512003202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20226528400 + 3493161 = 142220^2 + 1869^2 .

It is a cyclic number.

It is not a de Polignac number, because 20230021561 - 2⁷ = 20230021433 is a prime.

It is not a weakly prime, because it can be changed into another prime (20230021541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10115010780 + 10115010781.

It is an arithmetic number, because the mean of its divisors is an integer number (10115010781).

Almost surely, 2^20230021561 is an apocalyptic number.

It is an amenable number.

20230021561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20230021561 is an equidigital number, since it uses as much as digits as its factorization.

20230021561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 22.

Adding to 20230021561 its reverse (16512003202), we get a palindrome (36742024763).

The spelling of 20230021561 in words is "twenty billion, two hundred thirty million, twenty-one thousand, five hundred sixty-one".