21216872 has 32 divisors (see below), whose sum is σ = 41040000. Its totient is φ = 10278528.

The previous prime is 21216869. The next prime is 21216883. The reversal of 21216872 is 27861212.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37004 + ... + 37572.

It is an arithmetic number, because the mean of its divisors is an integer number (1282500).

Almost surely, 2^21216872 is an apocalyptic number.

It is an amenable number.

21216872 is a deficient number, since it is larger than the sum of its proper divisors (19823128).

21216872 is a wasteful number, since it uses less digits than its factorization.

21216872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 713 (or 709 counting only the distinct ones).

The product of its digits is 2688, while the sum is 29.

The square root of 21216872 is about 4606.1775910184. The cubic root of 21216872 is about 276.8389024477.

The spelling of 21216872 in words is "twenty-one million, two hundred sixteen thousand, eight hundred seventy-two".