21416281 has 2 divisors, whose sum is σ = 21416282. Its totient is φ = 21416280.

The previous prime is 21416183. The next prime is 21416321. The reversal of 21416281 is 18261412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21013056 + 403225 = 4584^2 + 635^2 .

It is a cyclic number.

It is not a de Polignac number, because 21416281 - 2⁹ = 21415769 is a prime.

It is a super-2 number, since 2×21416281² = 917314183741922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21410281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10708140 + 10708141.

It is an arithmetic number, because the mean of its divisors is an integer number (10708141).

Almost surely, 2^21416281 is an apocalyptic number.

It is an amenable number.

21416281 is a deficient number, since it is larger than the sum of its proper divisors (1).

21416281 is an equidigital number, since it uses as much as digits as its factorization.

21416281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 768, while the sum is 25.

The square root of 21416281 is about 4627.7727904468. The cubic root of 21416281 is about 277.7034992447.

Adding to 21416281 its reverse (18261412), we get a palindrome (39677693).

The spelling of 21416281 in words is "twenty-one million, four hundred sixteen thousand, two hundred eighty-one".