21211212220 has 48 divisors (see below), whose sum is σ = 48629349216. Its totient is φ = 7707392000.

The previous prime is 21211212173. The next prime is 21211212233. The reversal of 21211212220 is 2221211212.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21211212194 and 21211212203.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 264000 + ... + 334840.

It is an arithmetic number, because the mean of its divisors is an integer number (1013111442).

Almost surely, 2^21211212220 is an apocalyptic number.

21211212220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21211212220 is an abundant number, since it is smaller than the sum of its proper divisors (27418136996).

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

21211212220 is a wasteful number, since it uses less digits than its factorization.

21211212220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72222 (or 72220 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21211212220 its reverse (2221211212), we get a palindrome (23432423432).

The spelling of 21211212220 in words is "twenty-one billion, two hundred eleven million, two hundred twelve thousand, two hundred twenty".