1213021220 has 24 divisors (see below), whose sum is σ = 2548002744. Its totient is φ = 485083136.

The previous prime is 1213021207. The next prime is 1213021223. The reversal of 1213021220 is 221203121.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 17106496 + 1195914724 = 4136^2 + 34582^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1213021195 and 1213021204.

It is not an unprimeable number, because it can be changed into a prime (1213021223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 135194 + ... + 143886.

It is an arithmetic number, because the mean of its divisors is an integer number (106166781).

Almost surely, 2^1213021220 is an apocalyptic number.

1213021220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1213021220 is an abundant number, since it is smaller than the sum of its proper divisors (1334981524).

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

1213021220 is a wasteful number, since it uses less digits than its factorization.

1213021220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15679 (or 15677 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 1213021220 is about 34828.4541718406. The cubic root of 1213021220 is about 1066.4883918641.

Adding to 1213021220 its reverse (221203121), we get a palindrome (1434224341).

The spelling of 1213021220 in words is "one billion, two hundred thirteen million, twenty-one thousand, two hundred twenty".