21223616 has 28 divisors (see below), whose sum is σ = 44595288. Its totient is φ = 9987072.

The previous prime is 21223613. The next prime is 21223619. The reversal of 21223616 is 61632212.

It is an interprime number because it is at equal distance from previous prime (21223613) and next prime (21223619).

It is a super-2 number, since 2×21223616² = 900883752230912, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21223591 and 21223600.

It is not an unprimeable number, because it can be changed into a prime (21223613) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8666 + ... + 10841.

Almost surely, 2^21223616 is an apocalyptic number.

It is an amenable number.

21223616 is an abundant number, since it is smaller than the sum of its proper divisors (23371672).

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

21223616 is a wasteful number, since it uses less digits than its factorization.

21223616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19536 (or 19526 counting only the distinct ones).

The product of its digits is 864, while the sum is 23.

The square root of 21223616 is about 4606.9095932089. The cubic root of 21223616 is about 276.8682313669.

Adding to 21223616 its reverse (61632212), we get a palindrome (82855828).

The spelling of 21223616 in words is "twenty-one million, two hundred twenty-three thousand, six hundred sixteen".