21354181 has 2 divisors, whose sum is σ = 21354182. Its totient is φ = 21354180.

The previous prime is 21354167. The next prime is 21354191. The reversal of 21354181 is 18145312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17089956 + 4264225 = 4134^2 + 2065^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21354181 is a prime.

It is a super-2 number, since 2×21354181² = 912002092361522, which contains 22 as substring.

It is equal to p_1350934 and since 21354181 and 1350934 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21354191) 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, 10677090 + 10677091.

It is an arithmetic number, because the mean of its divisors is an integer number (10677091).

Almost surely, 2^21354181 is an apocalyptic number.

It is an amenable number.

21354181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21354181 is an equidigital number, since it uses as much as digits as its factorization.

21354181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 960, while the sum is 25.

The square root of 21354181 is about 4621.0584285421. The cubic root of 21354181 is about 277.4348238568.

Adding to 21354181 its reverse (18145312), we get a palindrome (39499493).

The spelling of 21354181 in words is "twenty-one million, three hundred fifty-four thousand, one hundred eighty-one".