21776534221 has 16 divisors (see below), whose sum is σ = 24032982960. Its totient is φ = 19603514880.

The previous prime is 21776534189. The next prime is 21776534231. The reversal of 21776534221 is 12243567712.

It can be written as a sum of positive squares in 8 ways, for example, as 14223186121 + 7553348100 = 119261^2 + 86910^2 .

It is a cyclic number.

It is not a de Polignac number, because 21776534221 - 2⁵ = 21776534189 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 (21776534231) 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 15 ways as a sum of consecutive naturals, for example, 1714731 + ... + 1727383.

It is an arithmetic number, because the mean of its divisors is an integer number (1502061435).

Almost surely, 2^21776534221 is an apocalyptic number.

It is an amenable number.

21776534221 is a deficient number, since it is larger than the sum of its proper divisors (2256448739).

21776534221 is a wasteful number, since it uses less digits than its factorization.

21776534221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15936.

The product of its digits is 141120, while the sum is 40.

The spelling of 21776534221 in words is "twenty-one billion, seven hundred seventy-six million, five hundred thirty-four thousand, two hundred twenty-one".