21200197 has 4 divisors (see below), whose sum is σ = 21253996. Its totient is φ = 21146400.

The previous prime is 21200191. The next prime is 21200209. The reversal of 21200197 is 79100212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8767521 + 12432676 = 2961^2 + 3526^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21200197 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200191) 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 3 ways as a sum of consecutive naturals, for example, 26304 + ... + 27097.

It is an arithmetic number, because the mean of its divisors is an integer number (5313499).

Almost surely, 2^21200197 is an apocalyptic number.

It is an amenable number.

21200197 is a deficient number, since it is larger than the sum of its proper divisors (53799).

21200197 is an equidigital number, since it uses as much as digits as its factorization.

21200197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53798.

The product of its (nonzero) digits is 252, while the sum is 22.

The square root of 21200197 is about 4604.3671660718. The cubic root of 21200197 is about 276.7663580030.

The spelling of 21200197 in words is "twenty-one million, two hundred thousand, one hundred ninety-seven".