21011011221 has 16 divisors (see below), whose sum is σ = 29258219520. Its totient is φ = 13386634800.

The previous prime is 21011011213. The next prime is 21011011223. The reversal of 21011011221 is 12211011012.

It is not a de Polignac number, because 21011011221 - 2³ = 21011011213 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21011011197 and 21011011206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011011223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 52861 + ... + 211698.

It is an arithmetic number, because the mean of its divisors is an integer number (1828638720).

Almost surely, 2^21011011221 is an apocalyptic number.

It is an amenable number.

21011011221 is a deficient number, since it is larger than the sum of its proper divisors (8247208299).

21011011221 is a wasteful number, since it uses less digits than its factorization.

21011011221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265736.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21011011221 its reverse (12211011012), we get a palindrome (33222022233).

The spelling of 21011011221 in words is "twenty-one billion, eleven million, eleven thousand, two hundred twenty-one".