21011221011 has 16 divisors (see below), whose sum is σ = 30858497280. Its totient is φ = 12610439520.

The previous prime is 21011220983. The next prime is 21011221019. The reversal of 21011221011 is 11012211012.

It is not a de Polignac number, because 21011221011 - 2⁶ = 21011220947 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21011221019) 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, 3087396 + ... + 3094193.

It is an arithmetic number, because the mean of its divisors is an integer number (1928656080).

Almost surely, 2^21011221011 is an apocalyptic number.

21011221011 is a deficient number, since it is larger than the sum of its proper divisors (9847276269).

21011221011 is a wasteful number, since it uses less digits than its factorization.

21011221011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6181706.

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

Adding to 21011221011 its reverse (11012211012), we get a palindrome (32023432023).

Subtracting from 21011221011 its reverse (11012211012), we obtain a palindrome (9999009999).

The spelling of 21011221011 in words is "twenty-one billion, eleven million, two hundred twenty-one thousand, eleven".