18015813729 has 9 divisors (see below), whose sum is σ = 26023423699. Its totient is φ = 12010274040.

The previous prime is 18015813703. The next prime is 18015813763. The reversal of 18015813729 is 92731851081.

The square root of 18015813729 is 134223.

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

18015813729 is a `hidden beast` number, since 18 + 0 + 1 + 581 + 37 + 29 = 666.

It can be written as a sum of positive squares in only one way, i.e., 65173329 + 17950640400 = 8073^2 + 133980^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 18015813729 - 2¹³ = 18015805537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18015813229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 380299 + ... + 425039.

Almost surely, 2^18015813729 is an apocalyptic number.

18015813729 is the 134223-rd square number.

18015813729 is the 67112-nd centered octagonal number.

It is an amenable number.

18015813729 is a deficient number, since it is larger than the sum of its proper divisors (8007609970).

18015813729 is an frugal number, since it uses more digits than its factorization.

18015813729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89488 (or 44744 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 45.

It can be divided in two parts, 18015 and 813729, that added together give a square (831744 = 912²).

The spelling of 18015813729 in words is "eighteen billion, fifteen million, eight hundred thirteen thousand, seven hundred twenty-nine".