21316863 has 8 divisors (see below), whose sum is σ = 29083648. Its totient is φ = 13880664.

The previous prime is 21316859. The next prime is 21316891. The reversal of 21316863 is 36861312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21316863 - 2² = 21316859 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21316863.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21316063) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 82495 + ... + 82752.

It is an arithmetic number, because the mean of its divisors is an integer number (3635456).

Almost surely, 2^21316863 is an apocalyptic number.

21316863 is a deficient number, since it is larger than the sum of its proper divisors (7766785).

21316863 is a wasteful number, since it uses less digits than its factorization.

21316863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165293.

The product of its digits is 5184, while the sum is 30.

The square root of 21316863 is about 4617.0188433664. The cubic root of 21316863 is about 277.2731170436.

The spelling of 21316863 in words is "twenty-one million, three hundred sixteen thousand, eight hundred sixty-three".