21210821181 has 12 divisors (see below), whose sum is σ = 33423112320. Its totient is φ = 12855043080.

The previous prime is 21210821179. The next prime is 21210821201. The reversal of 21210821181 is 18112801212.

It is not a de Polignac number, because 21210821181 - 2¹ = 21210821179 is a prime.

It is a super-2 number, since 2×21210821181² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210821161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 107125261 + ... + 107125458.

It is an arithmetic number, because the mean of its divisors is an integer number (2785259360).

Almost surely, 2^21210821181 is an apocalyptic number.

It is an amenable number.

21210821181 is a deficient number, since it is larger than the sum of its proper divisors (12212291139).

21210821181 is a wasteful number, since it uses less digits than its factorization.

21210821181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214250736 (or 214250733 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 27.

It can be divided in two parts, 212108 and 21181, that added together give a square (233289 = 483²).

The spelling of 21210821181 in words is "twenty-one billion, two hundred ten million, eight hundred twenty-one thousand, one hundred eighty-one".