21317236 has 24 divisors (see below), whose sum is σ = 38279304. Its totient is φ = 10383360.

The previous prime is 21317213. The next prime is 21317249. The reversal of 21317236 is 63271312.

It can be written as a sum of positive squares in 4 ways, for example, as 1425636 + 19891600 = 1194^2 + 4460^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21317236.

It is a congruent number.

It is an unprimeable number.

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, 40656 + ... + 41176.

It is an arithmetic number, because the mean of its divisors is an integer number (1594971).

Almost surely, 2^21317236 is an apocalyptic number.

It is an amenable number.

21317236 is a deficient number, since it is larger than the sum of its proper divisors (16962068).

21317236 is a wasteful number, since it uses less digits than its factorization.

21317236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 771 (or 769 counting only the distinct ones).

The product of its digits is 1512, while the sum is 25.

The square root of 21317236 is about 4617.0592372202. The cubic root of 21317236 is about 277.2747342651.

Adding to 21317236 its reverse (63271312), we get a palindrome (84588548).

The spelling of 21317236 in words is "twenty-one million, three hundred seventeen thousand, two hundred thirty-six".