21581353 has 2 divisors, whose sum is σ = 21581354. Its totient is φ = 21581352.

The previous prime is 21581341. The next prime is 21581369. The reversal of 21581353 is 35318512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20820969 + 760384 = 4563^2 + 872^2 .

It is a cyclic number.

It is not a de Polignac number, because 21581353 - 2⁹ = 21580841 is a prime.

It is not a weakly prime, because it can be changed into another prime (21081353) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10790676 + 10790677.

It is an arithmetic number, because the mean of its divisors is an integer number (10790677).

Almost surely, 2^21581353 is an apocalyptic number.

It is an amenable number.

21581353 is a deficient number, since it is larger than the sum of its proper divisors (1).

21581353 is an equidigital number, since it uses as much as digits as its factorization.

21581353 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3600, while the sum is 28.

The square root of 21581353 is about 4645.5734845119. The cubic root of 21581353 is about 278.4151664749.

Adding to 21581353 its reverse (35318512), we get a palindrome (56899865).

The spelling of 21581353 in words is "twenty-one million, five hundred eighty-one thousand, three hundred fifty-three".