21121212220220 has 48 divisors (see below), whose sum is σ = 50691389568960. Its totient is φ = 7241489869824.

The previous prime is 21121212220181. The next prime is 21121212220231. The reversal of 21121212220220 is 2202221212112.

It is a super-2 number, since 2×21121212220220² (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 = 21121212220192 and 21121212220201.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15410402 + ... + 16724918.

It is an arithmetic number, because the mean of its divisors is an integer number (1056070616020).

Almost surely, 2^{21121212220220} is an apocalyptic number.

21121212220220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21121212220220 is an abundant number, since it is smaller than the sum of its proper divisors (29570177348740).

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

21121212220220 is a wasteful number, since it uses less digits than its factorization.

21121212220220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1429302 (or 1429300 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21121212220220 its reverse (2202221212112), we get a palindrome (23323433432332).

The spelling of 21121212220220 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twelve million, two hundred twenty thousand, two hundred twenty".