21243716 has 12 divisors (see below), whose sum is σ = 40036332. Its totient is φ = 9804768.

The previous prime is 21243713. The next prime is 21243721. The reversal of 21243716 is 61734212.

It can be written as a sum of positive squares in 2 ways, for example, as 6002500 + 15241216 = 2450^2 + 3904^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is not an unprimeable number, because it can be changed into a prime (21243713) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 204215 + ... + 204318.

It is an arithmetic number, because the mean of its divisors is an integer number (3336361).

Almost surely, 2^21243716 is an apocalyptic number.

21243716 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21243716 is a deficient number, since it is larger than the sum of its proper divisors (18792616).

21243716 is a wasteful number, since it uses less digits than its factorization.

21243716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 408550 (or 408548 counting only the distinct ones).

The product of its digits is 2016, while the sum is 26.

The square root of 21243716 is about 4609.0905827506. The cubic root of 21243716 is about 276.9556072342.

Adding to 21243716 its reverse (61734212), we get a palindrome (82977928).

The spelling of 21243716 in words is "twenty-one million, two hundred forty-three thousand, seven hundred sixteen".