165581444889 has 63 divisors (see below), whose sum is σ = 288924812463. Its totient is φ = 94574021472.

The previous prime is 165581444857. The next prime is 165581444893. The reversal of 165581444889 is 988444185561.

It is a happy number.

The square root of 165581444889 is 406917.

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

165581444889 is a `hidden beast` number, since 1 + 6 + 5 + 5 + 8 + 144 + 488 + 9 = 666.

165581444889 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 12224619225 + 153356825664 = 110565^2 + 391608^2 .

It is a tau number, because it is divible by the number of its divisors (63).

It is not a de Polignac number, because 165581444889 - 2⁵ = 165581444857 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (165581444849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 76906237 + ... + 76908389.

Almost surely, 2^165581444889 is an apocalyptic number.

165581444889 is the 406917-th square number.

165581444889 is the 203459-th centered octagonal number.

It is an amenable number.

165581444889 is a deficient number, since it is larger than the sum of its proper divisors (123343367574).

165581444889 is an frugal number, since it uses more digits than its factorization.

165581444889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4338 (or 2163 counting only the distinct ones).

The product of its digits is 44236800, while the sum is 63.

The spelling of 165581444889 in words is "one hundred sixty-five billion, five hundred eighty-one million, four hundred forty-four thousand, eight hundred eighty-nine".