21263216 has 40 divisors (see below), whose sum is σ = 44726304. Its totient is φ = 9734400.

The previous prime is 21263213. The next prime is 21263233. The reversal of 21263216 is 61236212.

It is a junction number, because it is equal to n+sod(n) for n = 21263191 and 21263200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21263213) 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 7 ways as a sum of consecutive naturals, for example, 31070 + ... + 31746.

Almost surely, 2^21263216 is an apocalyptic number.

21263216 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21263216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22363152).

21263216 is an abundant number, since it is smaller than the sum of its proper divisors (23463088).

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

21263216 is a wasteful number, since it uses less digits than its factorization.

21263216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 849 (or 843 counting only the distinct ones).

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

The square root of 21263216 is about 4611.2054823007. The cubic root of 21263216 is about 277.0403222112.

Adding to 21263216 its reverse (61236212), we get a palindrome (82499428).

The spelling of 21263216 in words is "twenty-one million, two hundred sixty-three thousand, two hundred sixteen".