1221273648 has 180 divisors, whose sum is σ = 4032053688. Its totient is φ = 344010240.

The previous prime is 1221273593. The next prime is 1221273661. The reversal of 1221273648 is 8463721221.

It is a happy number.

1221273648 is a `hidden beast` number, since 1 + 2 + 2 + 1 + 2 + 7 + 3 + 648 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

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 35 ways as a sum of consecutive naturals, for example, 513903 + ... + 516273.

Almost surely, 2^1221273648 is an apocalyptic number.

1221273648 is a gapful number since it is divisible by the number (18) 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 1221273648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2016026844).

1221273648 is an abundant number, since it is smaller than the sum of its proper divisors (2810780040).

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

1221273648 is a wasteful number, since it uses less digits than its factorization.

1221273648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2472 (or 2456 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 1221273648 is about 34946.7258552214. The cubic root of 1221273648 is about 1068.9014398309.

Adding to 1221273648 its reverse (8463721221), we get a palindrome (9684994869).

The spelling of 1221273648 in words is "one billion, two hundred twenty-one million, two hundred seventy-three thousand, six hundred forty-eight".