21001221220111 has 8 divisors (see below), whose sum is σ = 22915705752144. Its totient is φ = 19087617121920.

The previous prime is 21001221220097. The next prime is 21001221220139. The reversal of 21001221220111 is 11102212210012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21001221220111 - 2³³ = 20992631285519 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 (21001221223111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 220058580 + ... + 220153993.

It is an arithmetic number, because the mean of its divisors is an integer number (2864463219018).

Almost surely, 2^{21001221220111} is an apocalyptic number.

21001221220111 is a deficient number, since it is larger than the sum of its proper divisors (1914484532033).

21001221220111 is a wasteful number, since it uses less digits than its factorization.

21001221220111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 440216921.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21001221220111 its reverse (11102212210012), we get a palindrome (32103433430123).

It can be divided in two parts, 2100122 and 1220111, that added together give a palindrome (3320233).

The spelling of 21001221220111 in words is "twenty-one trillion, one billion, two hundred twenty-one million, two hundred twenty thousand, one hundred eleven".