1221327631872 has 400 divisors, whose sum is σ = 3733501254912. Its totient is φ = 397379727360.

The previous prime is 1221327631813. The next prime is 1221327631897. The reversal of 1221327631872 is 2781367231221.

1221327631872 is a `hidden beast` number, since 1 + 2 + 2 + 1 + 3 + 2 + 7 + 631 + 8 + 7 + 2 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 303282723 + ... + 303286749.

Almost surely, 2^{1221327631872} is an apocalyptic number.

1221327631872 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 1221327631872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1866750627456).

1221327631872 is an abundant number, since it is smaller than the sum of its proper divisors (2512173623040).

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

1221327631872 is an equidigital number, since it uses as much as digits as its factorization.

1221327631872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4231 (or 4206 counting only the distinct ones).

The product of its digits is 338688, while the sum is 45.

The spelling of 1221327631872 in words is "one trillion, two hundred twenty-one billion, three hundred twenty-seven million, six hundred thirty-one thousand, eight hundred seventy-two".