21316806 has 24 divisors (see below), whose sum is σ = 52784784. Its totient is φ = 6090480.

The previous prime is 21316783. The next prime is 21316819. The reversal of 21316806 is 60861312.

It is a self number, because there is not a number n which added to its sum of digits gives 21316806.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 84465 + ... + 84716.

It is an arithmetic number, because the mean of its divisors is an integer number (2199366).

Almost surely, 2^21316806 is an apocalyptic number.

21316806 is an abundant number, since it is smaller than the sum of its proper divisors (31467978).

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

21316806 is a wasteful number, since it uses less digits than its factorization.

21316806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169196 (or 169193 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21316806 is about 4617.0126705479. The cubic root of 21316806 is about 277.2728699062.

It can be divided in two parts, 21316 and 806, that added together give a palindrome (22122).

The spelling of 21316806 in words is "twenty-one million, three hundred sixteen thousand, eight hundred six".