21181117 has 2 divisors, whose sum is σ = 21181118. Its totient is φ = 21181116.

The previous prime is 21181109. The next prime is 21181157. The reversal of 21181117 is 71118112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20169081 + 1012036 = 4491^2 + 1006^2 .

It is a cyclic number.

It is not a de Polignac number, because 21181117 - 2³ = 21181109 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21181157) 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, 10590558 + 10590559.

It is an arithmetic number, because the mean of its divisors is an integer number (10590559).

Almost surely, 2^21181117 is an apocalyptic number.

It is an amenable number.

21181117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21181117 is an equidigital number, since it uses as much as digits as its factorization.

21181117 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 112, while the sum is 22.

The square root of 21181117 is about 4602.2947537071. The cubic root of 21181117 is about 276.6833039462.

Adding to 21181117 its reverse (71118112), we get a palindrome (92299229).

The spelling of 21181117 in words is "twenty-one million, one hundred eighty-one thousand, one hundred seventeen".