21101221211220 has 72 divisors (see below), whose sum is σ = 64012359124896. Its totient is φ = 5626524503232.

The previous prime is 21101221211209. The next prime is 21101221211227. The reversal of 21101221211220 is 2211212210112.

21101221211220 is a `hidden beast` number, since 2 + 1 + 10 + 1 + 221 + 211 + 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 = 21101221211193 and 21101221211202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101221211227) 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 23 ways as a sum of consecutive naturals, for example, 2699362 + ... + 7034841.

Almost surely, 2^{21101221211220} is an apocalyptic number.

21101221211220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21101221211220 is an abundant number, since it is smaller than the sum of its proper divisors (42911137913676).

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

21101221211220 is a wasteful number, since it uses less digits than its factorization.

21101221211220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9746261 (or 9746256 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21101221211220 its reverse (2211212210112), we get a palindrome (23312433421332).

The spelling of 21101221211220 in words is "twenty-one trillion, one hundred one billion, two hundred twenty-one million, two hundred eleven thousand, two hundred twenty".