21201121 has 2 divisors, whose sum is σ = 21201122. Its totient is φ = 21201120.

The previous prime is 21201109. The next prime is 21201127. The reversal of 21201121 is 12110212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13220496 + 7980625 = 3636^2 + 2825^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201121 - 2¹³ = 21192929 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21201098 and 21201107.

It is not a weakly prime, because it can be changed into another prime (21201127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600560 + 10600561.

It is an arithmetic number, because the mean of its divisors is an integer number (10600561).

Almost surely, 2^21201121 is an apocalyptic number.

It is an amenable number.

21201121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201121 is an equidigital number, since it uses as much as digits as its factorization.

21201121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 21201121 is about 4604.4675045004. The cubic root of 21201121 is about 276.7703788524.

Adding to 21201121 its reverse (12110212), we get a palindrome (33311333).

Subtracting from 21201121 its reverse (12110212), we obtain a palindrome (9090909).

The spelling of 21201121 in words is "twenty-one million, two hundred one thousand, one hundred twenty-one".