66679117729 has 27 divisors (see below), whose sum is σ = 79798566393. Its totient is φ = 55553063328.

The previous prime is 66679117639. The next prime is 66679117741. The reversal of 66679117729 is 92771197666.

The square root of 66679117729 is 258223.

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

66679117729 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 4 ways, for example, as 38172172129 + 28506945600 = 195377^2 + 168840^2 .

It is not a de Polignac number, because 66679117729 - 2⁷ = 66679117601 is a prime.

It is a super-2 number, since 2×66679117729² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66679117529) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 66879259 + ... + 66880255.

It is an arithmetic number, because the mean of its divisors is an integer number (2955502459).

Almost surely, 2^66679117729 is an apocalyptic number.

66679117729 is the 258223-rd square number.

66679117729 is the 129112-nd centered octagonal number.

It is an amenable number.

66679117729 is a deficient number, since it is larger than the sum of its proper divisors (13119448664).

66679117729 is an frugal number, since it uses more digits than its factorization.

66679117729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2082 (or 1041 counting only the distinct ones).

The product of its digits is 12002256, while the sum is 61.

The spelling of 66679117729 in words is "sixty-six billion, six hundred seventy-nine million, one hundred seventeen thousand, seven hundred twenty-nine".