21310816 has 48 divisors (see below), whose sum is σ = 44241120. Its totient is φ = 10091520.

The previous prime is 21310813. The next prime is 21310819. The reversal of 21310816 is 61801312.

It is an interprime number because it is at equal distance from previous prime (21310813) and next prime (21310819).

It is a zygodrome in base 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21310813) 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, 48325 + ... + 48763.

It is an arithmetic number, because the mean of its divisors is an integer number (921690).

Almost surely, 2^21310816 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 21310816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22120560).

21310816 is an abundant number, since it is smaller than the sum of its proper divisors (22930304).

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

21310816 is a wasteful number, since it uses less digits than its factorization.

21310816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 527 (or 519 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 21310816 is about 4616.3639371263. The cubic root of 21310816 is about 277.2468963452.

The spelling of 21310816 in words is "twenty-one million, three hundred ten thousand, eight hundred sixteen".