21231221011 has 16 divisors (see below), whose sum is σ = 28506256128. Its totient is φ = 15271207200.

The previous prime is 21231221003. The next prime is 21231221017. The reversal of 21231221011 is 11012213212.

It is a cyclic number.

It is not a de Polignac number, because 21231221011 - 2³ = 21231221003 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21231221017) 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, 10604005 + ... + 10606006.

It is an arithmetic number, because the mean of its divisors is an integer number (1781641008).

Almost surely, 2^21231221011 is an apocalyptic number.

21231221011 is a deficient number, since it is larger than the sum of its proper divisors (7275035117).

21231221011 is a wasteful number, since it uses less digits than its factorization.

21231221011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21210042.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 21231221011 its reverse (11012213212), we get a palindrome (32243434223).

It can be divided in two parts, 21231 and 221011, that added together give a palindrome (242242).

The spelling of 21231221011 in words is "twenty-one billion, two hundred thirty-one million, two hundred twenty-one thousand, eleven".