21004585 has 12 divisors (see below), whose sum is σ = 29321028. Its totient is φ = 14402976.

The previous prime is 21004583. The next prime is 21004591. The reversal of 21004585 is 58540012.

It can be written as a sum of positive squares in 2 ways, for example, as 13046544 + 7958041 = 3612^2 + 2821^2 .

It is not a de Polignac number, because 21004585 - 2¹ = 21004583 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21004583) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 42622 + ... + 43111.

It is an arithmetic number, because the mean of its divisors is an integer number (2443419).

Almost surely, 2^21004585 is an apocalyptic number.

It is an amenable number.

21004585 is a deficient number, since it is larger than the sum of its proper divisors (8316443).

21004585 is an equidigital number, since it uses as much as digits as its factorization.

21004585 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85752 (or 85745 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 25.

The square root of 21004585 is about 4583.0759321661. The cubic root of 21004585 is about 275.9124950141.

Adding to 21004585 its reverse (58540012), we get a palindrome (79544597).

The spelling of 21004585 in words is "twenty-one million, four thousand, five hundred eighty-five".