1213221220 has 24 divisors (see below), whose sum is σ = 2556973944. Its totient is φ = 483534336.

The previous prime is 1213221203. The next prime is 1213221277. The reversal of 1213221220 is 221223121.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 175350564 + 1037870656 = 13242^2 + 32216^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1213221194 and 1213221203.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 103957 + ... + 115036.

It is an arithmetic number, because the mean of its divisors is an integer number (106540581).

Almost surely, 2^1213221220 is an apocalyptic number.

1213221220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1213221220 is an abundant number, since it is smaller than the sum of its proper divisors (1343752724).

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

1213221220 is a wasteful number, since it uses less digits than its factorization.

1213221220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219279 (or 219277 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 1213221220 is about 34831.3252690735. The cubic root of 1213221220 is about 1066.5470019838.

Adding to 1213221220 its reverse (221223121), we get a palindrome (1434444341).

The spelling of 1213221220 in words is "one billion, two hundred thirteen million, two hundred twenty-one thousand, two hundred twenty".