21360181 has 2 divisors, whose sum is σ = 21360182. Its totient is φ = 21360180.

The previous prime is 21360179. The next prime is 21360191. The reversal of 21360181 is 18106312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19580625 + 1779556 = 4425^2 + 1334^2 .

It is a cyclic number.

It is not a de Polignac number, because 21360181 - 2¹ = 21360179 is a prime.

It is a super-2 number, since 2×21360181² = 912514664705522, which contains 22 as substring.

Together with 21360179, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21360191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10680090 + 10680091.

It is an arithmetic number, because the mean of its divisors is an integer number (10680091).

Almost surely, 2^21360181 is an apocalyptic number.

It is an amenable number.

21360181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21360181 is an equidigital number, since it uses as much as digits as its factorization.

21360181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 21360181 is about 4621.7075848651. The cubic root of 21360181 is about 277.4608055457.

Adding to 21360181 its reverse (18106312), we get a palindrome (39466493).

The spelling of 21360181 in words is "twenty-one million, three hundred sixty thousand, one hundred eighty-one".