1281752721690 has 384 divisors, whose sum is σ = 3803918671872. Its totient is φ = 275160291840.

The previous prime is 1281752721673. The next prime is 1281752721709. The reversal of 1281752721690 is 961272571821.

It is a happy number.

It is a super-2 number, since 2×1281752721690² (a number of 25 digits) contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 319398124 + ... + 319402136.

It is an arithmetic number, because the mean of its divisors is an integer number (9906038208).

Almost surely, 2^{1281752721690} is an apocalyptic number.

1281752721690 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1281752721690, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1901959335936).

1281752721690 is an abundant number, since it is smaller than the sum of its proper divisors (2522165950182).

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

1281752721690 is a wasteful number, since it uses less digits than its factorization.

1281752721690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4274 (or 4267 counting only the distinct ones).

The product of its (nonzero) digits is 846720, while the sum is 51.

The spelling of 1281752721690 in words is "one trillion, two hundred eighty-one billion, seven hundred fifty-two million, seven hundred twenty-one thousand, six hundred ninety".