21361121 has 2 divisors, whose sum is σ = 21361122. Its totient is φ = 21361120.

The previous prime is 21361097. The next prime is 21361133. The reversal of 21361121 is 12116312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20151121 + 1210000 = 4489^2 + 1100^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21361121 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21361121.

It is not a weakly prime, because it can be changed into another prime (21361421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10680560 + 10680561.

It is an arithmetic number, because the mean of its divisors is an integer number (10680561).

Almost surely, 2^21361121 is an apocalyptic number.

It is an amenable number.

21361121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21361121 is an equidigital number, since it uses as much as digits as its factorization.

21361121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72, while the sum is 17.

The square root of 21361121 is about 4621.8092777613. The cubic root of 21361121 is about 277.4648755695.

Adding to 21361121 its reverse (12116312), we get a palindrome (33477433).

The spelling of 21361121 in words is "twenty-one million, three hundred sixty-one thousand, one hundred twenty-one".