21405337 has 2 divisors, whose sum is σ = 21405338. Its totient is φ = 21405336.

The previous prime is 21405313. The next prime is 21405359. The reversal of 21405337 is 73350412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20602521 + 802816 = 4539^2 + 896^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21405337 is a prime.

It is not a weakly prime, because it can be changed into another prime (21405367) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10702668 + 10702669.

It is an arithmetic number, because the mean of its divisors is an integer number (10702669).

Almost surely, 2^21405337 is an apocalyptic number.

It is an amenable number.

21405337 is a deficient number, since it is larger than the sum of its proper divisors (1).

21405337 is an equidigital number, since it uses as much as digits as its factorization.

21405337 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2520, while the sum is 25.

The square root of 21405337 is about 4626.5902131051. The cubic root of 21405337 is about 277.6561878101.

Adding to 21405337 its reverse (73350412), we get a palindrome (94755749).

The spelling of 21405337 in words is "twenty-one million, four hundred five thousand, three hundred thirty-seven".