21013585 has 8 divisors (see below), whose sum is σ = 25630056. Its totient is φ = 16535040.

The previous prime is 21013583. The next prime is 21013589. The reversal of 21013585 is 58531012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 529 + 21013056 = 23^2 + 4584^2 .

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

It is not a de Polignac number, because 21013585 - 2¹ = 21013583 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21013583) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34144 + ... + 34753.

It is an arithmetic number, because the mean of its divisors is an integer number (3203757).

Almost surely, 2^21013585 is an apocalyptic number.

It is an amenable number.

21013585 is a deficient number, since it is larger than the sum of its proper divisors (4616471).

21013585 is an equidigital number, since it uses as much as digits as its factorization.

21013585 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68963.

The product of its (nonzero) digits is 1200, while the sum is 25.

The square root of 21013585 is about 4584.0577003349. The cubic root of 21013585 is about 275.9518968537.

Adding to 21013585 its reverse (58531012), we get a palindrome (79544597).

The spelling of 21013585 in words is "twenty-one million, thirteen thousand, five hundred eighty-five".