21913216 has 48 divisors (see below), whose sum is σ = 47318310. Its totient is φ = 10103808.

The previous prime is 21913201. The next prime is 21913237. The reversal of 21913216 is 61231912.

It can be written as a sum of positive squares in 3 ways, for example, as 3594816 + 18318400 = 1896^2 + 4280^2 .

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 21126 + ... + 22138.

Almost surely, 2^21913216 is an apocalyptic number.

21913216 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 21913216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23659155).

21913216 is an abundant number, since it is smaller than the sum of its proper divisors (25405094).

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

21913216 is a wasteful number, since it uses less digits than its factorization.

21913216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1053 (or 1028 counting only the distinct ones).

The product of its digits is 648, while the sum is 25.

The square root of 21913216 is about 4681.1554129296. The cubic root of 21913216 is about 279.8350048335.

The spelling of 21913216 in words is "twenty-one million, nine hundred thirteen thousand, two hundred sixteen".