21201212012220 has 144 divisors (see below), whose sum is σ = 66702407754528. Its totient is φ = 5446390924800.

The previous prime is 21201212012209. The next prime is 21201212012243. The reversal of 21201212012220 is 2221021210212.

It is a happy number.

21201212012220 is a `hidden beast` number, since 2 + 120 + 121 + 201 + 2 + 220 = 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 = 21201212012193 and 21201212012202.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 15086574 + ... + 16431893.

It is an arithmetic number, because the mean of its divisors is an integer number (463211164962).

Almost surely, 2^{21201212012220} is an apocalyptic number.

21201212012220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21201212012220 is an abundant number, since it is smaller than the sum of its proper divisors (45501195742308).

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

21201212012220 is a wasteful number, since it uses less digits than its factorization.

21201212012220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31518620 (or 31518615 counting only the distinct ones).

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

Adding to 21201212012220 its reverse (2221021210212), we get a palindrome (23422233222432).

The spelling of 21201212012220 in words is "twenty-one trillion, two hundred one billion, two hundred twelve million, twelve thousand, two hundred twenty".