21081337 has 2 divisors, whose sum is σ = 21081338. Its totient is φ = 21081336.

The previous prime is 21081331. The next prime is 21081353. The reversal of 21081337 is 73318012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13920361 + 7160976 = 3731^2 + 2676^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21081337 is a prime.

It is not a weakly prime, because it can be changed into another prime (21081331) 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, 10540668 + 10540669.

It is an arithmetic number, because the mean of its divisors is an integer number (10540669).

Almost surely, 2^21081337 is an apocalyptic number.

It is an amenable number.

21081337 is a deficient number, since it is larger than the sum of its proper divisors (1).

21081337 is an equidigital number, since it uses as much as digits as its factorization.

21081337 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21081337 is about 4591.4417125779. The cubic root of 21081337 is about 276.2481533834.

Adding to 21081337 its reverse (73318012), we get a palindrome (94399349).

The spelling of 21081337 in words is "twenty-one million, eighty-one thousand, three hundred thirty-seven".