21200555 has 4 divisors (see below), whose sum is σ = 25440672. Its totient is φ = 16960440.

The previous prime is 21200539. The next prime is 21200563. The reversal of 21200555 is 55500212.

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

It is not a de Polignac number, because 21200555 - 2⁴ = 21200539 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2120051 + ... + 2120060.

It is an arithmetic number, because the mean of its divisors is an integer number (6360168).

Almost surely, 2^21200555 is an apocalyptic number.

21200555 is a deficient number, since it is larger than the sum of its proper divisors (4240117).

21200555 is an equidigital number, since it uses as much as digits as its factorization.

21200555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4240116.

The product of its (nonzero) digits is 500, while the sum is 20.

The square root of 21200555 is about 4604.4060420428. The cubic root of 21200555 is about 276.7679158785.

Adding to 21200555 its reverse (55500212), we get a palindrome (76700767).

The spelling of 21200555 in words is "twenty-one million, two hundred thousand, five hundred fifty-five".