21243516 has 24 divisors (see below), whose sum is σ = 56649600. Its totient is φ = 6069552.

The previous prime is 21243503. The next prime is 21243517. The reversal of 21243516 is 61534212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 126366 + ... + 126533.

It is an arithmetic number, because the mean of its divisors is an integer number (2360400).

Almost surely, 2^21243516 is an apocalyptic number.

It is an amenable number.

21243516 is an abundant number, since it is smaller than the sum of its proper divisors (35406084).

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

21243516 is a wasteful number, since it uses less digits than its factorization.

21243516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 252913 (or 252911 counting only the distinct ones).

The product of its digits is 1440, while the sum is 24.

The square root of 21243516 is about 4609.0688864455. The cubic root of 21243516 is about 276.9547380941.

Adding to 21243516 its reverse (61534212), we get a palindrome (82777728).

The spelling of 21243516 in words is "twenty-one million, two hundred forty-three thousand, five hundred sixteen".