21626321 has 2 divisors, whose sum is σ = 21626322. Its totient is φ = 21626320.

The previous prime is 21626281. The next prime is 21626359. The reversal of 21626321 is 12362612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21529600 + 96721 = 4640^2 + 311^2 .

It is a cyclic number.

It is not a de Polignac number, because 21626321 - 2¹⁰ = 21625297 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21626621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10813160 + 10813161.

It is an arithmetic number, because the mean of its divisors is an integer number (10813161).

Almost surely, 2^21626321 is an apocalyptic number.

It is an amenable number.

21626321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21626321 is an equidigital number, since it uses as much as digits as its factorization.

21626321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 23.

The square root of 21626321 is about 4650.4108420655. The cubic root of 21626321 is about 278.6084056360.

Adding to 21626321 its reverse (12362612), we get a palindrome (33988933).

The spelling of 21626321 in words is "twenty-one million, six hundred twenty-six thousand, three hundred twenty-one".