21102120108 has 48 divisors (see below), whose sum is σ = 54773278560. Its totient is φ = 7025801472.

The previous prime is 21102120107. The next prime is 21102120133. The reversal of 21102120108 is 80102120112.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21102120101) 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 15 ways as a sum of consecutive naturals, for example, 21441 + ... + 206552.

It is an arithmetic number, because the mean of its divisors is an integer number (1141109970).

Almost surely, 2^21102120108 is an apocalyptic number.

It is an amenable number.

21102120108 is an abundant number, since it is smaller than the sum of its proper divisors (33671158452).

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

21102120108 is a wasteful number, since it uses less digits than its factorization.

21102120108 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228863 (or 228855 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

The spelling of 21102120108 in words is "twenty-one billion, one hundred two million, one hundred twenty thousand, one hundred eight".