21201212202120 has 384 divisors, whose sum is σ = 72744108877440. Its totient is φ = 5552626360320.

The previous prime is 21201212202089. The next prime is 21201212202133. The reversal of 21201212202120 is 2120221210212.

It is a happy number.

21201212202120 is a `hidden beast` number, since 21 + 201 + 212 + 20 + 212 + 0 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 21201212202093 and 21201212202102.

It is an unprimeable number.

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 95 ways as a sum of consecutive naturals, for example, 123426214 + ... + 123597866.

It is an arithmetic number, because the mean of its divisors is an integer number (189437783535).

Almost surely, 2^{21201212202120} is an apocalyptic number.

21201212202120 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 21201212202120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36372054438720).

21201212202120 is an abundant number, since it is smaller than the sum of its proper divisors (51542896675320).

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

21201212202120 is a wasteful number, since it uses less digits than its factorization.

21201212202120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171907 (or 171891 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21201212202120 its reverse (2120221210212), we get a palindrome (23321433412332).

It can be divided in two parts, 2120121 and 2202120, that added together give a square (4322241 = 2079²).

The spelling of 21201212202120 in words is "twenty-one trillion, two hundred one billion, two hundred twelve million, two hundred two thousand, one hundred twenty".