21002121122000 has 80 divisors (see below), whose sum is σ = 50802546626832. Its totient is φ = 8397636249600.

The previous prime is 21002121121997. The next prime is 21002121122033. The reversal of 21002121122000 is 22112120012.

It can be written as a sum of positive squares in 8 ways, for example, as 1770528294544 + 19231592827456 = 1330612^2 + 4385384^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3227684 + ... + 7240316.

Almost surely, 2^{21002121122000} is an apocalyptic number.

21002121122000 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 21002121122000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25401273313416).

21002121122000 is an abundant number, since it is smaller than the sum of its proper divisors (29800425504832).

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

21002121122000 is a wasteful number, since it uses less digits than its factorization.

21002121122000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4015273 (or 4015257 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21002121122000 its reverse (22112120012), we get a palindrome (21024233242012).

The spelling of 21002121122000 in words is "twenty-one trillion, two billion, one hundred twenty-one million, one hundred twenty-two thousand".