21585853 has 2 divisors, whose sum is σ = 21585854. Its totient is φ = 21585852.

The previous prime is 21585847. The next prime is 21585901. The reversal of 21585853 is 35858512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19686969 + 1898884 = 4437^2 + 1378^2 .

It is a cyclic number.

It is not a de Polignac number, because 21585853 - 2⁹ = 21585341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21585253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10792926 + 10792927.

It is an arithmetic number, because the mean of its divisors is an integer number (10792927).

Almost surely, 2^21585853 is an apocalyptic number.

It is an amenable number.

21585853 is a deficient number, since it is larger than the sum of its proper divisors (1).

21585853 is an equidigital number, since it uses as much as digits as its factorization.

21585853 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48000, while the sum is 37.

The square root of 21585853 is about 4646.0577912893. The cubic root of 21585853 is about 278.4345162221.

It can be divided in two parts, 215 and 85853, that added together give a palindrome (86068).

The spelling of 21585853 in words is "twenty-one million, five hundred eighty-five thousand, eight hundred fifty-three".