1213521220 has 12 divisors (see below), whose sum is σ = 2548394604. Its totient is φ = 485408480.

The previous prime is 1213521173. The next prime is 1213521233. The reversal of 1213521220 is 221253121.

It can be written as a sum of positive squares in 2 ways, for example, as 683508736 + 530012484 = 26144^2 + 23022^2 .

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 30338011 + ... + 30338050.

It is an arithmetic number, because the mean of its divisors is an integer number (212366217).

Almost surely, 2^1213521220 is an apocalyptic number.

1213521220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1213521220 is an abundant number, since it is smaller than the sum of its proper divisors (1334873384).

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

1213521220 is a wasteful number, since it uses less digits than its factorization.

1213521220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60676070 (or 60676068 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 1213521220 is about 34835.6314712393. The cubic root of 1213521220 is about 1066.6349050872.

Adding to 1213521220 its reverse (221253121), we get a palindrome (1434774341).

The spelling of 1213521220 in words is "one billion, two hundred thirteen million, five hundred twenty-one thousand, two hundred twenty".