21208818281 has 16 divisors (see below), whose sum is σ = 24543918720. Its totient is φ = 17950584960.

The previous prime is 21208818277. The next prime is 21208818307. The reversal of 21208818281 is 18281880212.

It is not a de Polignac number, because 21208818281 - 2² = 21208818277 is a prime.

It is a super-2 number, since 2×21208818281² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21208818251) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 449126 + ... + 494096.

It is an arithmetic number, because the mean of its divisors is an integer number (1533994920).

Almost surely, 2^21208818281 is an apocalyptic number.

It is an amenable number.

21208818281 is a deficient number, since it is larger than the sum of its proper divisors (3335100439).

21208818281 is an equidigital number, since it uses as much as digits as its factorization.

21208818281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45824.

The product of its (nonzero) digits is 32768, while the sum is 41.

The spelling of 21208818281 in words is "twenty-one billion, two hundred eight million, eight hundred eighteen thousand, two hundred eighty-one".