21106121 has 2 divisors, whose sum is σ = 21106122. Its totient is φ = 21106120.

The previous prime is 21106109. The next prime is 21106147. The reversal of 21106121 is 12160112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19678096 + 1428025 = 4436^2 + 1195^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21106121 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21106096 and 21106105.

It is not a weakly prime, because it can be changed into another prime (21106181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10553060 + 10553061.

It is an arithmetic number, because the mean of its divisors is an integer number (10553061).

Almost surely, 2^21106121 is an apocalyptic number.

It is an amenable number.

21106121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21106121 is an equidigital number, since it uses as much as digits as its factorization.

21106121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 14.

The square root of 21106121 is about 4594.1398542056. The cubic root of 21106121 is about 276.3563668389.

Adding to 21106121 its reverse (12160112), we get a palindrome (33266233).

The spelling of 21106121 in words is "twenty-one million, one hundred six thousand, one hundred twenty-one".