1661273275872 has 576 divisors, whose sum is σ = 5424903880704. Its totient is φ = 435540188160.

The previous prime is 1661273275861. The next prime is 1661273275897. The reversal of 1661273275872 is 2785723721661.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1399555663 + ... + 1399556849.

It is an arithmetic number, because the mean of its divisors is an integer number (9418235904).

Almost surely, 2^{1661273275872} is an apocalyptic number.

1661273275872 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 1661273275872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2712451940352).

1661273275872 is an abundant number, since it is smaller than the sum of its proper divisors (3763630604832).

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

1661273275872 is a wasteful number, since it uses less digits than its factorization.

1661273275872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1411 (or 1380 counting only the distinct ones).

The product of its digits is 11854080, while the sum is 57.

The spelling of 1661273275872 in words is "one trillion, six hundred sixty-one billion, two hundred seventy-three million, two hundred seventy-five thousand, eight hundred seventy-two".