21000312 has 48 divisors (see below), whose sum is σ = 58420440. Its totient is φ = 6810048.

The previous prime is 21000307. The next prime is 21000313. The reversal of 21000312 is 21300012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21000294 and 21000303.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000313) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1278 + ... + 6605.

Almost surely, 2^21000312 is an apocalyptic number.

It is an amenable number.

21000312 is an abundant number, since it is smaller than the sum of its proper divisors (37420128).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21000312 is a wasteful number, since it uses less digits than its factorization.

21000312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7932 (or 7925 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21000312 is about 4582.6097368203. The cubic root of 21000312 is about 275.8937839557.

Adding to 21000312 its reverse (21300012), we get a palindrome (42300324).

It can be divided in two parts, 21000 and 312, that added together give a palindrome (21312).

The spelling of 21000312 in words is "twenty-one million, three hundred twelve", and thus it is an aban number.