21003312 has 40 divisors (see below), whose sum is σ = 59192640. Its totient is φ = 6364480.

The previous prime is 21003299. The next prime is 21003329. The reversal of 21003312 is 21330012.

It is a happy number.

It is a super-2 number, since 2×21003312² = 882278229938688, which contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19362 + ... + 20417.

It is an arithmetic number, because the mean of its divisors is an integer number (1479816).

Almost surely, 2^21003312 is an apocalyptic number.

21003312 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21003312 is an abundant number, since it is smaller than the sum of its proper divisors (38189328).

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

21003312 is a wasteful number, since it uses less digits than its factorization.

21003312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39801 (or 39795 counting only the distinct ones).

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

The square root of 21003312 is about 4582.9370495349. The cubic root of 21003312 is about 275.9069209342.

Adding to 21003312 its reverse (21330012), we get a palindrome (42333324).

The spelling of 21003312 in words is "twenty-one million, three thousand, three hundred twelve".