21030312 has 16 divisors (see below), whose sum is σ = 52575840. Its totient is φ = 7010096.

The previous prime is 21030301. The next prime is 21030313. The reversal of 21030312 is 21303012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is not an unprimeable number, because it can be changed into a prime (21030313) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 438108 + ... + 438155.

It is an arithmetic number, because the mean of its divisors is an integer number (3285990).

Almost surely, 2^21030312 is an apocalyptic number.

It is an amenable number.

21030312 is an abundant number, since it is smaller than the sum of its proper divisors (31545528).

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

21030312 is a wasteful number, since it uses less digits than its factorization.

21030312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 876272 (or 876268 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21030312 is about 4585.8818126943. The cubic root of 21030312 is about 276.0250974867.

Adding to 21030312 its reverse (21303012), we get a palindrome (42333324).

The spelling of 21030312 in words is "twenty-one million, thirty thousand, three hundred twelve".