21463616 has 42 divisors (see below), whose sum is σ = 44999910. Its totient is φ = 10156032.

The previous prime is 21463613. The next prime is 21463621. The reversal of 21463616 is 61636412.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 12222016 + 9241600 = 3496^2 + 3040^2 .

It is not an unprimeable number, because it can be changed into a prime (21463613) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 22640 + ... + 23568.

Almost surely, 2^21463616 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 21463616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22499955).

21463616 is an abundant number, since it is smaller than the sum of its proper divisors (23536294).

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

21463616 is an equidigital number, since it uses as much as digits as its factorization.

21463616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 979 (or 950 counting only the distinct ones).

The product of its digits is 5184, while the sum is 29.

The square root of 21463616 is about 4632.8841988550. The cubic root of 21463616 is about 277.9079452988.

The spelling of 21463616 in words is "twenty-one million, four hundred sixty-three thousand, six hundred sixteen".