21712585 has 4 divisors (see below), whose sum is σ = 26055108. Its totient is φ = 17370064.

The previous prime is 21712567. The next prime is 21712631. The reversal of 21712585 is 58521712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2238016 + 19474569 = 1496^2 + 4413^2 .

It is a cyclic number.

It is not a de Polignac number, because 21712585 - 2¹¹ = 21710537 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 2171254 + ... + 2171263.

It is an arithmetic number, because the mean of its divisors is an integer number (6513777).

Almost surely, 2^21712585 is an apocalyptic number.

It is an amenable number.

21712585 is a deficient number, since it is larger than the sum of its proper divisors (4342523).

21712585 is an equidigital number, since it uses as much as digits as its factorization.

21712585 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4342522.

The product of its digits is 5600, while the sum is 31.

The square root of 21712585 is about 4659.6764909165. The cubic root of 21712585 is about 278.9783559131.

The spelling of 21712585 in words is "twenty-one million, seven hundred twelve thousand, five hundred eighty-five".