21200255217 has 24 divisors (see below), whose sum is σ = 30939504960. Its totient is φ = 13987360800.

The previous prime is 21200255203. The next prime is 21200255243. The reversal of 21200255217 is 71255200212.

It is not a de Polignac number, because 21200255217 - 2¹¹ = 21200253169 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21200255257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3013458 + ... + 3020484.

It is an arithmetic number, because the mean of its divisors is an integer number (1289146040).

Almost surely, 2^21200255217 is an apocalyptic number.

It is an amenable number.

21200255217 is a deficient number, since it is larger than the sum of its proper divisors (9739249743).

21200255217 is a wasteful number, since it uses less digits than its factorization.

21200255217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10453 (or 10450 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 27.

Adding to 21200255217 its reverse (71255200212), we get a palindrome (92455455429).

The spelling of 21200255217 in words is "twenty-one billion, two hundred million, two hundred fifty-five thousand, two hundred seventeen".