1221312552 has 64 divisors (see below), whose sum is σ = 3244147200. Its totient is φ = 382057920.

The previous prime is 1221312511. The next prime is 1221312559. The reversal of 1221312552 is 2552131221.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (1221312559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36277 + ... + 61307.

It is an arithmetic number, because the mean of its divisors is an integer number (50689800).

Almost surely, 2^1221312552 is an apocalyptic number.

1221312552 is a gapful number since it is divisible by the number (12) 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 1221312552, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1622073600).

1221312552 is an abundant number, since it is smaller than the sum of its proper divisors (2022834648).

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

1221312552 is a wasteful number, since it uses less digits than its factorization.

1221312552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25166 (or 25162 counting only the distinct ones).

The product of its digits is 1200, while the sum is 24.

The square root of 1221312552 is about 34947.2824694568. The cubic root of 1221312552 is about 1068.9127897579.

Adding to 1221312552 its reverse (2552131221), we get a palindrome (3773443773).

The spelling of 1221312552 in words is "one billion, two hundred twenty-one million, three hundred twelve thousand, five hundred fifty-two".