21253585 has 8 divisors (see below), whose sum is σ = 25854120. Its totient is φ = 16769664.

The previous prime is 21253543. The next prime is 21253591. The reversal of 21253585 is 58535212.

It can be written as a sum of positive squares in 4 ways, for example, as 3873024 + 17380561 = 1968^2 + 4169^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21253585 is a prime.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 28750 + ... + 29479.

It is an arithmetic number, because the mean of its divisors is an integer number (3231765).

Almost surely, 2^21253585 is an apocalyptic number.

It is an amenable number.

21253585 is a deficient number, since it is larger than the sum of its proper divisors (4600535).

21253585 is an equidigital number, since it uses as much as digits as its factorization.

21253585 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58307.

The product of its digits is 12000, while the sum is 31.

The square root of 21253585 is about 4610.1610600932. The cubic root of 21253585 is about 276.9984881774.

Adding to 21253585 its reverse (58535212), we get a palindrome (79788797).

The spelling of 21253585 in words is "twenty-one million, two hundred fifty-three thousand, five hundred eighty-five".