21013312 has 14 divisors (see below), whose sum is σ = 41698418. Its totient is φ = 10506624.

The previous prime is 21013303. The next prime is 21013357. The reversal of 21013312 is 21331012.

It can be written as a sum of positive squares in only one way, i.e., 21013056 + 256 = 4584^2 + 16^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21013292 and 21013301.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 164103 + ... + 164230.

Almost surely, 2^21013312 is an apocalyptic number.

It is an amenable number.

21013312 is a deficient number, since it is larger than the sum of its proper divisors (20685106).

21013312 is an equidigital number, since it uses as much as digits as its factorization.

21013312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328345 (or 328335 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21013312 is about 4584.0279231261. The cubic root of 21013312 is about 275.9507018301.

Adding to 21013312 its reverse (21331012), we get a palindrome (42344324).

The spelling of 21013312 in words is "twenty-one million, thirteen thousand, three hundred twelve".