21201221212020 has 96 divisors (see below), whose sum is σ = 66101816471040. Its totient is φ = 5641447996800.

The previous prime is 21201221212001. The next prime is 21201221212091. The reversal of 21201221212020 is 2021212210212.

It is a happy number.

21201221212020 is a `hidden beast` number, since 21 + 201 + 221 + 21 + 202 + 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 = 21201221211984 and 21201221212002.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 42149031 + ... + 42649070.

It is an arithmetic number, because the mean of its divisors is an integer number (688560588240).

Almost surely, 2^{21201221212020} is an apocalyptic number.

21201221212020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21201221212020 is an abundant number, since it is smaller than the sum of its proper divisors (44900595259020).

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

21201221212020 is a wasteful number, since it uses less digits than its factorization.

21201221212020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84798582 (or 84798574 counting only the distinct ones).

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

Adding to 21201221212020 its reverse (2021212210212), we get a palindrome (23222433422232).

The spelling of 21201221212020 in words is "twenty-one trillion, two hundred one billion, two hundred twenty-one million, two hundred twelve thousand, twenty".