1221222220 has 12 divisors (see below), whose sum is σ = 2564566704. Its totient is φ = 488488880.

The previous prime is 1221222203. The next prime is 1221222229. The reversal of 1221222220 is 222221221.

It is a junction number, because it is equal to n+sod(n) for n = 1221222194 and 1221222203.

It is not an unprimeable number, because it can be changed into a prime (1221222229) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30530536 + ... + 30530575.

It is an arithmetic number, because the mean of its divisors is an integer number (213713892).

Almost surely, 2^1221222220 is an apocalyptic number.

1221222220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221222220 is an abundant number, since it is smaller than the sum of its proper divisors (1343344484).

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

1221222220 is a wasteful number, since it uses less digits than its factorization.

1221222220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61061120 (or 61061118 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 1221222220 is about 34945.9900417773. The cubic root of 1221222220 is about 1068.8864357585.

Adding to 1221222220 its reverse (222221221), we get a palindrome (1443443441).

Subtracting from 1221222220 its reverse (222221221), we obtain a palindrome (999000999).

The spelling of 1221222220 in words is "one billion, two hundred twenty-one million, two hundred twenty-two thousand, two hundred twenty".