1281665665020 has 384 divisors, whose sum is σ = 3943683072000. Its totient is φ = 309136684032.

The previous prime is 1281665665019. The next prime is 1281665665039. The reversal of 1281665665020 is 205665661821.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 4528853799 + ... + 4528854081.

It is an arithmetic number, because the mean of its divisors is an integer number (10270008000).

Almost surely, 2^{1281665665020} is an apocalyptic number.

1281665665020 is a gapful number since it is divisible by the number (10) 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 1281665665020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1971841536000).

1281665665020 is an abundant number, since it is smaller than the sum of its proper divisors (2662017406980).

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

1281665665020 is a wasteful number, since it uses less digits than its factorization.

1281665665020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 849 (or 847 counting only the distinct ones).

The product of its (nonzero) digits is 1036800, while the sum is 48.

The spelling of 1281665665020 in words is "one trillion, two hundred eighty-one billion, six hundred sixty-five million, six hundred sixty-five thousand, twenty".