21686368 has 24 divisors (see below), whose sum is σ = 46577160. Its totient is φ = 9857280.

The previous prime is 21686347. The next prime is 21686383. The reversal of 21686368 is 86368612.

It is a self number, because there is not a number n which added to its sum of digits gives 21686368.

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, 30453 + ... + 31156.

It is an arithmetic number, because the mean of its divisors is an integer number (1940715).

Almost surely, 2^21686368 is an apocalyptic number.

It is an amenable number.

21686368 is an abundant number, since it is smaller than the sum of its proper divisors (24890792).

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

21686368 is a wasteful number, since it uses less digits than its factorization.

21686368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61630 (or 61622 counting only the distinct ones).

The product of its digits is 82944, while the sum is 40.

The square root of 21686368 is about 4656.8624630753. The cubic root of 21686368 is about 278.8660259548.

The spelling of 21686368 in words is "twenty-one million, six hundred eighty-six thousand, three hundred sixty-eight".