221212100220 has 24 divisors (see below), whose sum is σ = 619393880784. Its totient is φ = 58989893376.

The previous prime is 221212100189. The next prime is 221212100227. The reversal of 221212100220 is 22001212122.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 221212100220.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221212100227) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 1843434109 + ... + 1843434228.

It is an arithmetic number, because the mean of its divisors is an integer number (25808078366).

Almost surely, 2^221212100220 is an apocalyptic number.

221212100220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221212100220 is an abundant number, since it is smaller than the sum of its proper divisors (398181780564).

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

221212100220 is a wasteful number, since it uses less digits than its factorization.

221212100220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3686868349 (or 3686868347 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 221212100220 its reverse (22001212122), we get a palindrome (243213312342).

The spelling of 221212100220 in words is "two hundred twenty-one billion, two hundred twelve million, one hundred thousand, two hundred twenty".