21172906109908 has 36 divisors (see below), whose sum is σ = 43237955979540. Its totient is φ = 9045477662592.

The previous prime is 21172906109881. The next prime is 21172906110047. The reversal of 21172906109908 is 80990160927112.

It can be written as a sum of positive squares in 2 ways, for example, as 13049881701444 + 8123024408464 = 3612462^2 + 2850092^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 170324353 + ... + 170448616.

It is an arithmetic number, because the mean of its divisors is an integer number (1201054332765).

Almost surely, 2^{21172906109908} is an apocalyptic number.

21172906109908 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21172906109908 is an abundant number, since it is smaller than the sum of its proper divisors (22065049869632).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21172906109908 is a wasteful number, since it uses less digits than its factorization.

21172906109908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 340773304 (or 340773295 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 55.

The spelling of 21172906109908 in words is "twenty-one trillion, one hundred seventy-two billion, nine hundred six million, one hundred nine thousand, nine hundred eight".