1781123665523 has 8 divisors (see below), whose sum is σ = 1881836787600. Its totient is φ = 1681107520608.

The previous prime is 1781123665513. The next prime is 1781123665549. The reversal of 1781123665523 is 3255663211871.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1781123665523 - 2⁴ = 1781123665507 is a prime.

It is a super-3 number, since 3×1781123665523³ (a number of 38 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1781123665513) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 174239036 + ... + 174249257.

It is an arithmetic number, because the mean of its divisors is an integer number (235229598450).

Almost surely, 2^{1781123665523} is an apocalyptic number.

1781123665523 is a deficient number, since it is larger than the sum of its proper divisors (100713122077).

1781123665523 is a wasteful number, since it uses less digits than its factorization.

1781123665523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 348488581.

The product of its digits is 1814400, while the sum is 50.

The spelling of 1781123665523 in words is "one trillion, seven hundred eighty-one billion, one hundred twenty-three million, six hundred sixty-five thousand, five hundred twenty-three".