21011101122221 has 4 divisors (see below), whose sum is σ = 24012686996832. Its totient is φ = 18009515247612.

The previous prime is 21011101122211. The next prime is 21011101122223. The reversal of 21011101122221 is 12222110111012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21011101122221 - 2³⁸ = 20736223215277 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21011101122221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011101122223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1500792937295 + ... + 1500792937308.

It is an arithmetic number, because the mean of its divisors is an integer number (6003171749208).

Almost surely, 2^{21011101122221} is an apocalyptic number.

It is an amenable number.

21011101122221 is a deficient number, since it is larger than the sum of its proper divisors (3001585874611).

21011101122221 is an equidigital number, since it uses as much as digits as its factorization.

21011101122221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3001585874610.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21011101122221 its reverse (12222110111012), we get a palindrome (33233211233233).

The spelling of 21011101122221 in words is "twenty-one trillion, eleven billion, one hundred one million, one hundred twenty-two thousand, two hundred twenty-one".