21324181 has 2 divisors, whose sum is σ = 21324182. Its totient is φ = 21324180.

The previous prime is 21324161. The next prime is 21324203. The reversal of 21324181 is 18142312.

It is a happy number.

It is an a-pointer prime, because the next prime (21324203) can be obtained adding 21324181 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19980900 + 1343281 = 4470^2 + 1159^2 .

It is a cyclic number.

It is not a de Polignac number, because 21324181 - 2⁷ = 21324053 is a prime.

It is a super-2 number, since 2×21324181² = 909441390641522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21324101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10662090 + 10662091.

It is an arithmetic number, because the mean of its divisors is an integer number (10662091).

Almost surely, 2^21324181 is an apocalyptic number.

It is an amenable number.

21324181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21324181 is an equidigital number, since it uses as much as digits as its factorization.

21324181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 384, while the sum is 22.

The square root of 21324181 is about 4617.8112780840. The cubic root of 21324181 is about 277.3048423577.

Adding to 21324181 its reverse (18142312), we get a palindrome (39466493).

The spelling of 21324181 in words is "twenty-one million, three hundred twenty-four thousand, one hundred eighty-one".