21316568 has 96 divisors (see below), whose sum is σ = 51710400. Its totient is φ = 8160768.

The previous prime is 21316553. The next prime is 21316579. The reversal of 21316568 is 86561312.

It is a happy number.

It is a congruent number.

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 23 ways as a sum of consecutive naturals, for example, 239468 + ... + 239556.

It is an arithmetic number, because the mean of its divisors is an integer number (538650).

Almost surely, 2^21316568 is an apocalyptic number.

21316568 is a gapful number since it is divisible by the number (28) 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 21316568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25855200).

21316568 is an abundant number, since it is smaller than the sum of its proper divisors (30393832).

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

21316568 is a wasteful number, since it uses less digits than its factorization.

21316568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 169 (or 158 counting only the distinct ones).

The product of its digits is 8640, while the sum is 32.

The square root of 21316568 is about 4616.9868962344. The cubic root of 21316568 is about 277.2718379944.

The spelling of 21316568 in words is "twenty-one million, three hundred sixteen thousand, five hundred sixty-eight".