21220716 has 48 divisors (see below), whose sum is σ = 54286848. Its totient is φ = 6398400.

The previous prime is 21220711. The next prime is 21220733. The reversal of 21220716 is 61702212.

It is a junction number, because it is equal to n+sod(n) for n = 21220692 and 21220701.

It is not an unprimeable number, because it can be changed into a prime (21220711) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 49021 + ... + 49451.

It is an arithmetic number, because the mean of its divisors is an integer number (1130976).

Almost surely, 2^21220716 is an apocalyptic number.

It is an amenable number.

21220716 is an abundant number, since it is smaller than the sum of its proper divisors (33066132).

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

21220716 is a wasteful number, since it uses less digits than its factorization.

21220716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 822 (or 820 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 21220716 is about 4606.5948378385. The cubic root of 21220716 is about 276.8556203452.

Adding to 21220716 its reverse (61702212), we get a palindrome (82922928).

The spelling of 21220716 in words is "twenty-one million, two hundred twenty thousand, seven hundred sixteen".