1211220220 has 72 divisors (see below), whose sum is σ = 3054360960. Its totient is φ = 401869440.

The previous prime is 1211220217. The next prime is 1211220223. The reversal of 1211220220 is 220221121.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1211220217) and next prime (1211220223).

It is a self number, because there is not a number n which added to its sum of digits gives 1211220220.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211220223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10446 + ... + 50314.

It is an arithmetic number, because the mean of its divisors is an integer number (42421680).

Almost surely, 2^1211220220 is an apocalyptic number.

1211220220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1211220220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1527180480).

1211220220 is an abundant number, since it is smaller than the sum of its proper divisors (1843140740).

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

1211220220 is a wasteful number, since it uses less digits than its factorization.

1211220220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39923 (or 39914 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 1211220220 is about 34802.5892714896. The cubic root of 1211220220 is about 1065.9603172961.

Adding to 1211220220 its reverse (220221121), we get a palindrome (1431441341).

Subtracting from 1211220220 its reverse (220221121), we obtain a palindrome (990999099).

The spelling of 1211220220 in words is "one billion, two hundred eleven million, two hundred twenty thousand, two hundred twenty".