21317200 has 60 divisors (see below), whose sum is σ = 51721020. Its totient is φ = 8442880.

The previous prime is 21317147. The next prime is 21317209. The reversal of 21317200 is 271312.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 1175056 + 20142144 = 1084^2 + 4488^2 .

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21317209) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 54606 + ... + 54994.

It is an arithmetic number, because the mean of its divisors is an integer number (862017).

Almost surely, 2^21317200 is an apocalyptic number.

21317200 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21317200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25860510).

21317200 is an abundant number, since it is smaller than the sum of its proper divisors (30403820).

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

21317200 is a wasteful number, since it uses less digits than its factorization.

21317200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 544 (or 533 counting only the distinct ones).

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 21317200 is about 4617.0553386331. The cubic root of 21317200 is about 277.2745781802.

Adding to 21317200 its reverse (271312), we get a palindrome (21588512).

The spelling of 21317200 in words is "twenty-one million, three hundred seventeen thousand, two hundred".