221221231020 has 72 divisors (see below), whose sum is σ = 671284046160. Its totient is φ = 58970674560.

The previous prime is 221221231009. The next prime is 221221231027. The reversal of 221221231020 is 20132122122.

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 = 221221230984 and 221221231002.

It is not an unprimeable number, because it can be changed into a prime (221221231027) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 269191 + ... + 717569.

It is an arithmetic number, because the mean of its divisors is an integer number (9323389530).

Almost surely, 2^221221231020 is an apocalyptic number.

221221231020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221221231020 is an abundant number, since it is smaller than the sum of its proper divisors (450062815140).

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

221221231020 is a wasteful number, since it uses less digits than its factorization.

221221231020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 451135 (or 451130 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 221221231020 its reverse (20132122122), we get a palindrome (241353353142).

The spelling of 221221231020 in words is "two hundred twenty-one billion, two hundred twenty-one million, two hundred thirty-one thousand, twenty".