21121212211220 has 144 divisors (see below), whose sum is σ = 49051675948800. Its totient is φ = 7633526883840.

The previous prime is 21121212211213. The next prime is 21121212211247. The reversal of 21121212211220 is 2211221212112.

It is a super-2 number, since 2×21121212211220² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21121212211192 and 21121212211201.

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, 451217057 + ... + 451263863.

Almost surely, 2^{21121212211220} is an apocalyptic number.

21121212211220 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 21121212211220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24525837974400).

21121212211220 is an abundant number, since it is smaller than the sum of its proper divisors (27930463737580).

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

21121212211220 is a wasteful number, since it uses less digits than its factorization.

21121212211220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47974 (or 47961 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 20.

Adding to 21121212211220 its reverse (2211221212112), we get a palindrome (23332433423332).

The spelling of 21121212211220 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twelve million, two hundred eleven thousand, two hundred twenty".