21102100000000 has 324 divisors, whose sum is σ = 55753864032132. Its totient is φ = 7943680000000.

The previous prime is 21102099999991. The next prime is 21102100000001. The reversal of 21102100000000 is 120112.

It can be written as a sum of positive squares in 18 ways, for example, as 1420597004544 + 19681502995456 = 1191888^2 + 4436384^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102100000001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1699993794 + ... + 1700006206.

Almost surely, 2^{21102100000000} is an apocalyptic number.

21102100000000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21102100000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27876932016066).

21102100000000 is an abundant number, since it is smaller than the sum of its proper divisors (34651764032132).

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

21102100000000 is an frugal number, since it uses more digits than its factorization.

21102100000000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12486 (or 12437 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 7.

Adding to 21102100000000 its reverse (120112), we get a palindrome (21102100120112).

The spelling of 21102100000000 in words is "twenty-one trillion, one hundred two billion, one hundred million", and thus it is an aban number.