20543405221 has 4 divisors (see below), whose sum is σ = 21206095744. Its totient is φ = 19880714700.

The previous prime is 20543405219. The next prime is 20543405257. The reversal of 20543405221 is 12250434502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20543405221 - 2¹ = 20543405219 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20543405221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20543405291) 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 in 3 ways as a sum of consecutive naturals, for example, 331345215 + ... + 331345276.

It is an arithmetic number, because the mean of its divisors is an integer number (5301523936).

Almost surely, 2^20543405221 is an apocalyptic number.

It is an amenable number.

20543405221 is a deficient number, since it is larger than the sum of its proper divisors (662690523).

20543405221 is an equidigital number, since it uses as much as digits as its factorization.

20543405221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 662690522.

The product of its (nonzero) digits is 9600, while the sum is 28.

Adding to 20543405221 its reverse (12250434502), we get a palindrome (32793839723).

The spelling of 20543405221 in words is "twenty billion, five hundred forty-three million, four hundred five thousand, two hundred twenty-one".