165781023857604 has 117 divisors (see below), whose sum is σ = 435224198354911. Its totient is φ = 55254083745240.

The previous prime is 165781023857551. The next prime is 165781023857627. The reversal of 165781023857604 is 406758320187561.

It is a happy number.

The square root of 165781023857604 is 12875598.

It is a perfect power (a square), and thus also a powerful number.

165781023857604 is a `hidden beast` number, since 1 + 6 + 5 + 7 + 8 + 10 + 2 + 3 + 8 + 5 + 7 + 604 = 666.

165781023857604 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 38 ways as a sum of consecutive naturals, for example, 18772617469 + ... + 18772626299.

Almost surely, 2^{165781023857604} is an apocalyptic number.

165781023857604 is the 12875598-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 165781023857604

165781023857604 is an abundant number, since it is smaller than the sum of its proper divisors (269443174497307).

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

165781023857604 is an frugal number, since it uses more digits than its factorization.

165781023857604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17702 (or 8836 counting only the distinct ones).

The product of its (nonzero) digits is 67737600, while the sum is 63.

The spelling of 165781023857604 in words is "one hundred sixty-five trillion, seven hundred eighty-one billion, twenty-three million, eight hundred fifty-seven thousand, six hundred four".