21007912 has 16 divisors (see below), whose sum is σ = 40036500. Its totient is φ = 10331520.

The previous prime is 21007891. The next prime is 21007913. The reversal of 21007912 is 21970012.

It can be written as a sum of positive squares in 2 ways, for example, as 20921476 + 86436 = 4574^2 + 294^2 .

It is not an unprimeable number, because it can be changed into a prime (21007913) 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, 21037 + ... + 22012.

Almost surely, 2^21007912 is an apocalyptic number.

It is an amenable number.

21007912 is a deficient number, since it is larger than the sum of its proper divisors (19028588).

21007912 is a wasteful number, since it uses less digits than its factorization.

21007912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43116 (or 43112 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 22.

The square root of 21007912 is about 4583.4388836331. The cubic root of 21007912 is about 275.9270618719.

Adding to 21007912 its reverse (21970012), we get a palindrome (42977924).

The spelling of 21007912 in words is "twenty-one million, seven thousand, nine hundred twelve".