1791221257728 has 840 divisors, whose sum is σ = 6413162267952. Its totient is φ = 497757560832.

The previous prime is 1791221257711. The next prime is 1791221257733. The reversal of 1791221257728 is 8277521221971.

1791221257728 is a `hidden beast` number, since 17 + 9 + 1 + 22 + 12 + 577 + 28 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 83 ways as a sum of consecutive naturals, for example, 676697301 + ... + 676699947.

Almost surely, 2^{1791221257728} is an apocalyptic number.

1791221257728 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 1791221257728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3206581133976).

1791221257728 is an abundant number, since it is smaller than the sum of its proper divisors (4621941010224).

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

1791221257728 is an frugal number, since it uses more digits than its factorization.

1791221257728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2734 (or 2696 counting only the distinct ones).

The product of its digits is 1975680, while the sum is 54.

The spelling of 1791221257728 in words is "one trillion, seven hundred ninety-one billion, two hundred twenty-one million, two hundred fifty-seven thousand, seven hundred twenty-eight".