21001316 has 24 divisors (see below), whose sum is σ = 42119616. Its totient is φ = 8975520.

The previous prime is 21001247. The next prime is 21001319. The reversal of 21001316 is 61310012.

It is a Harshad number since it is a multiple of its sum of digits (14).

It is a self number, because there is not a number n which added to its sum of digits gives 21001316.

It is not an unprimeable number, because it can be changed into a prime (21001319) 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, 12095 + ... + 13721.

It is an arithmetic number, because the mean of its divisors is an integer number (1754984).

Almost surely, 2^21001316 is an apocalyptic number.

It is an amenable number.

21001316 is an abundant number, since it is smaller than the sum of its proper divisors (21118300).

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

21001316 is a wasteful number, since it uses less digits than its factorization.

21001316 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2099 (or 2097 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 21001316 is about 4582.7192800782. The cubic root of 21001316 is about 275.8981806038.

Adding to 21001316 its reverse (61310012), we get a palindrome (82311328).

The spelling of 21001316 in words is "twenty-one million, one thousand, three hundred sixteen".