21416321 has 2 divisors, whose sum is σ = 21416322. Its totient is φ = 21416320.

The previous prime is 21416281. The next prime is 21416333. The reversal of 21416321 is 12361412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11424400 + 9991921 = 3380^2 + 3161^2 .

It is a cyclic number.

It is not a de Polignac number, because 21416321 - 2²² = 17222017 is a prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 21416293 and 21416302.

It is not a weakly prime, because it can be changed into another prime (21416341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10708160 + 10708161.

It is an arithmetic number, because the mean of its divisors is an integer number (10708161).

Almost surely, 2^21416321 is an apocalyptic number.

It is an amenable number.

21416321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21416321 is an equidigital number, since it uses as much as digits as its factorization.

21416321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 20.

The square root of 21416321 is about 4627.7771121782. Note that the first 3 decimals coincide. The cubic root of 21416321 is about 277.7036721370.

Adding to 21416321 its reverse (12361412), we get a palindrome (33777733).

The spelling of 21416321 in words is "twenty-one million, four hundred sixteen thousand, three hundred twenty-one".