21211688 has 16 divisors (see below), whose sum is σ = 41055360. Its totient is φ = 10263600.

The previous prime is 21211643. The next prime is 21211709. The reversal of 21211688 is 88611212.

It is a self number, because there is not a number n which added to its sum of digits gives 21211688.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42518 + ... + 43013.

It is an arithmetic number, because the mean of its divisors is an integer number (2565960).

Almost surely, 2^21211688 is an apocalyptic number.

It is an amenable number.

21211688 is a deficient number, since it is larger than the sum of its proper divisors (19843672).

21211688 is a wasteful number, since it uses less digits than its factorization.

21211688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85568 (or 85564 counting only the distinct ones).

The product of its digits is 1536, while the sum is 29.

The square root of 21211688 is about 4605.6148340911. The cubic root of 21211688 is about 276.8163535729.

The spelling of 21211688 in words is "twenty-one million, two hundred eleven thousand, six hundred eighty-eight".