20544788021 has 2 divisors, whose sum is σ = 20544788022. Its totient is φ = 20544788020.

The previous prime is 20544787993. The next prime is 20544788029. The reversal of 20544788021 is 12088744502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20467594225 + 77193796 = 143065^2 + 8786^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20544788021 is a prime.

It is a super-3 number, since 3×20544788021³ (a number of 32 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20544788021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20544788029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10272394010 + 10272394011.

It is an arithmetic number, because the mean of its divisors is an integer number (10272394011).

Almost surely, 2^20544788021 is an apocalyptic number.

It is an amenable number.

20544788021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20544788021 is an equidigital number, since it uses as much as digits as its factorization.

20544788021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 143360, while the sum is 41.

The spelling of 20544788021 in words is "twenty billion, five hundred forty-four million, seven hundred eighty-eight thousand, twenty-one".