1213361556 has 48 divisors (see below), whose sum is σ = 3112919040. Its totient is φ = 364785120.

The previous prime is 1213361551. The next prime is 1213361561. The reversal of 1213361556 is 6551633121.

It is an interprime number because it is at equal distance from previous prime (1213361551) and next prime (1213361561).

It is a super-2 number, since 2×1213361556² = 2944492531157482272, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1213361551) 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 15 ways as a sum of consecutive naturals, for example, 19426 + ... + 52953.

It is an arithmetic number, because the mean of its divisors is an integer number (64852480).

Almost surely, 2^1213361556 is an apocalyptic number.

It is an amenable number.

1213361556 is an abundant number, since it is smaller than the sum of its proper divisors (1899557484).

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

1213361556 is a wasteful number, since it uses less digits than its factorization.

1213361556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72524 (or 72522 counting only the distinct ones).

The product of its digits is 16200, while the sum is 33.

The square root of 1213361556 is about 34833.3397192977. The cubic root of 1213361556 is about 1066.5881236872.

Adding to 1213361556 its reverse (6551633121), we get a palindrome (7764994677).

The spelling of 1213361556 in words is "one billion, two hundred thirteen million, three hundred sixty-one thousand, five hundred fifty-six".