21716856 has 128 divisors (see below), whose sum is σ = 70502400. Its totient is φ = 6065280.

The previous prime is 21716831. The next prime is 21716857. The reversal of 21716856 is 65861712.

It is a Harshad number since it is a multiple of its sum of digits (36).

Its product of digits (20160) is a multiple of the sum of its prime divisors (336).

It is a self number, because there is not a number n which added to its sum of digits gives 21716856.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21716857) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 80001 + ... + 80271.

It is an arithmetic number, because the mean of its divisors is an integer number (550800).

Almost surely, 2^21716856 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 21716856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35251200).

21716856 is an abundant number, since it is smaller than the sum of its proper divisors (48785544).

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

21716856 is a wasteful number, since it uses less digits than its factorization.

21716856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 346 (or 336 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21716856 is about 4660.1347619999. The cubic root of 21716856 is about 278.9966469709.

The spelling of 21716856 in words is "twenty-one million, seven hundred sixteen thousand, eight hundred fifty-six".