21111221211 has 8 divisors (see below), whose sum is σ = 28180915200. Its totient is φ = 14057837352.

The previous prime is 21111221207. The next prime is 21111221213. The reversal of 21111221211 is 11212211112.

It is a happy number.

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

It is not a de Polignac number, because 21111221211 - 2² = 21111221207 is a prime.

It is a super-2 number, since 2×21111221211² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21111221213) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4074511 + ... + 4079688.

It is an arithmetic number, because the mean of its divisors is an integer number (3522614400).

Almost surely, 2^21111221211 is an apocalyptic number.

21111221211 is a deficient number, since it is larger than the sum of its proper divisors (7069693989).

21111221211 is an equidigital number, since it uses as much as digits as its factorization.

21111221211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8155065.

The product of its digits is 16, while the sum is 15.

Adding to 21111221211 its reverse (11212211112), we get a palindrome (32323432323).

The spelling of 21111221211 in words is "twenty-one billion, one hundred eleven million, two hundred twenty-one thousand, two hundred eleven".