21585427 has 4 divisors (see below), whose sum is σ = 22855176. Its totient is φ = 20315680.

The previous prime is 21585413. The next prime is 21585433. The reversal of 21585427 is 72458512.

It is a happy number.

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

It is not a de Polignac number, because 21585427 - 2¹¹ = 21583379 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21585392 and 21585401.

It is not an unprimeable number, because it can be changed into a prime (21585127) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 634849 + ... + 634882.

It is an arithmetic number, because the mean of its divisors is an integer number (5713794).

Almost surely, 2^21585427 is an apocalyptic number.

21585427 is a deficient number, since it is larger than the sum of its proper divisors (1269749).

21585427 is a wasteful number, since it uses less digits than its factorization.

21585427 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1269748.

The product of its digits is 22400, while the sum is 34.

The square root of 21585427 is about 4646.0119457444. The cubic root of 21585427 is about 278.4326845613.

The spelling of 21585427 in words is "twenty-one million, five hundred eighty-five thousand, four hundred twenty-seven".