21686016 has 144 divisors (see below), whose sum is σ = 67108608. Its totient is φ = 6144000.

The previous prime is 21685967. The next prime is 21686023. The reversal of 21686016 is 61068612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 143541 + ... + 143691.

It is an arithmetic number, because the mean of its divisors is an integer number (466032).

Almost surely, 2^21686016 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21686016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33554304).

21686016 is an abundant number, since it is smaller than the sum of its proper divisors (45422592).

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

21686016 is a wasteful number, since it uses less digits than its factorization.

21686016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198 (or 184 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 21686016 is about 4656.8246692355. The cubic root of 21686016 is about 278.8645171518.

The spelling of 21686016 in words is "twenty-one million, six hundred eighty-six thousand, sixteen".