21085312 has 16 divisors (see below), whose sum is σ = 42006150. Its totient is φ = 10542592.

The previous prime is 21085289. The next prime is 21085343. The reversal of 21085312 is 21358012.

It can be written as a sum of positive squares in only one way, i.e., 18181696 + 2903616 = 4264^2 + 1704^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82237 + ... + 82492.

Almost surely, 2^21085312 is an apocalyptic number.

It is an amenable number.

21085312 is a deficient number, since it is larger than the sum of its proper divisors (20920838).

21085312 is an equidigital number, since it uses as much as digits as its factorization.

21085312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164743 (or 164731 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 21085312 is about 4591.8745627467. The cubic root of 21085312 is about 276.2655149862.

The spelling of 21085312 in words is "twenty-one million, eighty-five thousand, three hundred twelve".