21144181 has 2 divisors, whose sum is σ = 21144182. Its totient is φ = 21144180.

The previous prime is 21144173. The next prime is 21144187. The reversal of 21144181 is 18144112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19945156 + 1199025 = 4466^2 + 1095^2 .

It is a cyclic number.

It is not a de Polignac number, because 21144181 - 2³ = 21144173 is a prime.

It is a super-2 number, since 2×21144181² = 894152780321522, 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 (21144187) 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, 10572090 + 10572091.

It is an arithmetic number, because the mean of its divisors is an integer number (10572091).

Almost surely, 2^21144181 is an apocalyptic number.

It is an amenable number.

21144181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21144181 is an equidigital number, since it uses as much as digits as its factorization.

21144181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 256, while the sum is 22.

The square root of 21144181 is about 4598.2802219960. The cubic root of 21144181 is about 276.5223819855.

Adding to 21144181 its reverse (18144112), we get a palindrome (39288293).

The spelling of 21144181 in words is "twenty-one million, one hundred forty-four thousand, one hundred eighty-one".