21401321 has 2 divisors, whose sum is σ = 21401322. Its totient is φ = 21401320.

The previous prime is 21401299. The next prime is 21401323. The reversal of 21401321 is 12310412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21114025 + 287296 = 4595^2 + 536^2 .

It is a cyclic number.

It is not a de Polignac number, because 21401321 - 2⁶ = 21401257 is a prime.

Together with 21401323, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21401296 and 21401305.

It is not a weakly prime, because it can be changed into another prime (21401323) 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, 10700660 + 10700661.

It is an arithmetic number, because the mean of its divisors is an integer number (10700661).

Almost surely, 2^21401321 is an apocalyptic number.

It is an amenable number.

21401321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21401321 is an equidigital number, since it uses as much as digits as its factorization.

21401321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21401321 is about 4626.1561798106. The cubic root of 21401321 is about 277.6388224058.

Adding to 21401321 its reverse (12310412), we get a palindrome (33711733).

Subtracting from 21401321 its reverse (12310412), we obtain a palindrome (9090909).

The spelling of 21401321 in words is "twenty-one million, four hundred one thousand, three hundred twenty-one".