20981320543 has 2 divisors, whose sum is σ = 20981320544. Its totient is φ = 20981320542.

The previous prime is 20981320531. The next prime is 20981320561. The reversal of 20981320543 is 34502318902.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20981320543 is a prime.

It is a super-2 number, since 2×20981320543² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20981320573) 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, 10490660271 + 10490660272.

It is an arithmetic number, because the mean of its divisors is an integer number (10490660272).

Almost surely, 2^20981320543 is an apocalyptic number.

20981320543 is a deficient number, since it is larger than the sum of its proper divisors (1).

20981320543 is an equidigital number, since it uses as much as digits as its factorization.

20981320543 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 51840, while the sum is 37.

The spelling of 20981320543 in words is "twenty billion, nine hundred eighty-one million, three hundred twenty thousand, five hundred forty-three".