20751520861 has 2 divisors, whose sum is σ = 20751520862. Its totient is φ = 20751520860.

The previous prime is 20751520859. The next prime is 20751520913. The reversal of 20751520861 is 16802515702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12559460761 + 8192060100 = 112069^2 + 90510^2 .

It is a cyclic number.

It is not a de Polignac number, because 20751520861 - 2¹ = 20751520859 is a prime.

Together with 20751520859, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 20751520861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20751523861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10375760430 + 10375760431.

It is an arithmetic number, because the mean of its divisors is an integer number (10375760431).

Almost surely, 2^20751520861 is an apocalyptic number.

It is an amenable number.

20751520861 is a deficient number, since it is larger than the sum of its proper divisors (1).

20751520861 is an equidigital number, since it uses as much as digits as its factorization.

20751520861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 33600, while the sum is 37.

The spelling of 20751520861 in words is "twenty billion, seven hundred fifty-one million, five hundred twenty thousand, eight hundred sixty-one".