21220443511 has 32 divisors (see below), whose sum is σ = 23180636160. Its totient is φ = 19351747584.

The previous prime is 21220443481. The next prime is 21220443521. The reversal of 21220443511 is 11534402212.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21220443511 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220443521) 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 31 ways as a sum of consecutive naturals, for example, 25783846 + ... + 25784668.

It is an arithmetic number, because the mean of its divisors is an integer number (724394880).

Almost surely, 2^21220443511 is an apocalyptic number.

21220443511 is a deficient number, since it is larger than the sum of its proper divisors (1960192649).

21220443511 is a wasteful number, since it uses less digits than its factorization.

21220443511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1255.

The product of its (nonzero) digits is 1920, while the sum is 25.

Adding to 21220443511 its reverse (11534402212), we get a palindrome (32754845723).

The spelling of 21220443511 in words is "twenty-one billion, two hundred twenty million, four hundred forty-three thousand, five hundred eleven".