21500244355 has 4 divisors (see below), whose sum is σ = 25800293232. Its totient is φ = 17200195480.

The previous prime is 21500244349. The next prime is 21500244361. The reversal of 21500244355 is 55344200512.

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

It is an interprime number because it is at equal distance from previous prime (21500244349) and next prime (21500244361).

It is not a de Polignac number, because 21500244355 - 2³ = 21500244347 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 2150024431 + ... + 2150024440.

It is an arithmetic number, because the mean of its divisors is an integer number (6450073308).

Almost surely, 2^21500244355 is an apocalyptic number.

21500244355 is a deficient number, since it is larger than the sum of its proper divisors (4300048877).

21500244355 is an equidigital number, since it uses as much as digits as its factorization.

21500244355 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4300048876.

The product of its (nonzero) digits is 24000, while the sum is 31.

Adding to 21500244355 its reverse (55344200512), we get a palindrome (76844444867).

The spelling of 21500244355 in words is "twenty-one billion, five hundred million, two hundred forty-four thousand, three hundred fifty-five".