21100122221 has 2 divisors, whose sum is σ = 21100122222. Its totient is φ = 21100122220.

The previous prime is 21100122167. The next prime is 21100122257. The reversal of 21100122221 is 12222100112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12318558121 + 8781564100 = 110989^2 + 93710^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21100122221 is a prime.

It is a super-2 number, since 2×21100122221² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21100122196 and 21100122205.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21100122521) 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 as a sum of consecutive naturals, namely, 10550061110 + 10550061111.

It is an arithmetic number, because the mean of its divisors is an integer number (10550061111).

Almost surely, 2^21100122221 is an apocalyptic number.

It is an amenable number.

21100122221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100122221 is an equidigital number, since it uses as much as digits as its factorization.

21100122221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21100122221 its reverse (12222100112), we get a palindrome (33322222333).

The spelling of 21100122221 in words is "twenty-one billion, one hundred million, one hundred twenty-two thousand, two hundred twenty-one".