21708200 has 24 divisors (see below), whose sum is σ = 50472030. Its totient is φ = 8683200.

The previous prime is 21708191. The next prime is 21708209. The reversal of 21708200 is 280712.

It is an interprime number because it is at equal distance from previous prime (21708191) and next prime (21708209).

It can be written as a sum of positive squares in 3 ways, for example, as 19731364 + 1976836 = 4442^2 + 1406^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (21708209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 54071 + ... + 54470.

Almost surely, 2^21708200 is an apocalyptic number.

21708200 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21708200 is an abundant number, since it is smaller than the sum of its proper divisors (28763830).

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

21708200 is a wasteful number, since it uses less digits than its factorization.

21708200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108557 (or 108548 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 21708200 is about 4659.2059409303. The cubic root of 21708200 is about 278.9595741413.

Adding to 21708200 its reverse (280712), we get a palindrome (21988912).

The spelling of 21708200 in words is "twenty-one million, seven hundred eight thousand, two hundred".