21321337 has 2 divisors, whose sum is σ = 21321338. Its totient is φ = 21321336.

The previous prime is 21321331. The next prime is 21321341. The reversal of 21321337 is 73312312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17464041 + 3857296 = 4179^2 + 1964^2 .

It is a cyclic number.

It is not a de Polignac number, because 21321337 - 2²³ = 12932729 is a prime.

It is a super-2 number, since 2×21321337² = 909198822935138, which contains 22 as substring.

It is a plaindrome in base 13 and base 16.

It is not a weakly prime, because it can be changed into another prime (21321331) 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, 10660668 + 10660669.

It is an arithmetic number, because the mean of its divisors is an integer number (10660669).

Almost surely, 2^21321337 is an apocalyptic number.

It is an amenable number.

21321337 is a deficient number, since it is larger than the sum of its proper divisors (1).

21321337 is an equidigital number, since it uses as much as digits as its factorization.

21321337 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 756, while the sum is 22.

The square root of 21321337 is about 4617.5033297227. The cubic root of 21321337 is about 277.2925137867.

Adding to 21321337 its reverse (73312312), we get a palindrome (94633649).

The spelling of 21321337 in words is "twenty-one million, three hundred twenty-one thousand, three hundred thirty-seven".