21008712 has 16 divisors (see below), whose sum is σ = 52521840. Its totient is φ = 7002896.

The previous prime is 21008681. The next prime is 21008749. The reversal of 21008712 is 21780012.

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 in 3 ways as a sum of consecutive naturals, for example, 437658 + ... + 437705.

It is an arithmetic number, because the mean of its divisors is an integer number (3282615).

Almost surely, 2^21008712 is an apocalyptic number.

It is an amenable number.

21008712 is an abundant number, since it is smaller than the sum of its proper divisors (31513128).

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

21008712 is a wasteful number, since it uses less digits than its factorization.

21008712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 875372 (or 875368 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 21008712 is about 4583.5261535198. The cubic root of 21008712 is about 275.9305643435.

Adding to 21008712 its reverse (21780012), we get a palindrome (42788724).

The spelling of 21008712 in words is "twenty-one million, eight thousand, seven hundred twelve".