21230616 has 64 divisors (see below), whose sum is σ = 58423680. Its totient is φ = 6375680.

The previous prime is 21230611. The next prime is 21230617. The reversal of 21230616 is 61603212.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21230592 and 21230601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21230611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35875 + ... + 36461.

It is an arithmetic number, because the mean of its divisors is an integer number (912870).

Almost surely, 2^21230616 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 21230616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29211840).

21230616 is an abundant number, since it is smaller than the sum of its proper divisors (37193064).

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

21230616 is a wasteful number, since it uses less digits than its factorization.

21230616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 744 (or 740 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 21230616 is about 4607.6692589638. The cubic root of 21230616 is about 276.8986670317.

Adding to 21230616 its reverse (61603212), we get a palindrome (82833828).

The spelling of 21230616 in words is "twenty-one million, two hundred thirty thousand, six hundred sixteen".