21820716 has 18 divisors (see below), whose sum is σ = 55158012. Its totient is φ = 7273560.

The previous prime is 21820709. The next prime is 21820751. The reversal of 21820716 is 61702812.

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×21820716² = 952287293505312, which contains 22 as substring.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21820716.

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 5 ways as a sum of consecutive naturals, for example, 303030 + ... + 303101.

It is an arithmetic number, because the mean of its divisors is an integer number (3064334).

Almost surely, 2^21820716 is an apocalyptic number.

It is an amenable number.

21820716 is an abundant number, since it is smaller than the sum of its proper divisors (33337296).

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

21820716 is a wasteful number, since it uses less digits than its factorization.

21820716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 606141 (or 606136 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 21820716 is about 4671.2649250497. The cubic root of 21820716 is about 279.4407032831.

The spelling of 21820716 in words is "twenty-one million, eight hundred twenty thousand, seven hundred sixteen".