28666354685409 has 81 divisors (see below), whose sum is σ = 48547515300921. Its totient is φ = 16252468525440.

The previous prime is 28666354685401. The next prime is 28666354685429. The reversal of 28666354685409 is 90458645366682.

The square root of 28666354685409 is 5354097.

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

It can be written as a sum of positive squares in 4 ways, for example, as 10908322700625 + 17758031984784 = 3302775^2 + 4214028^2 .

It is not a de Polignac number, because 28666354685409 - 2³ = 28666354685401 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28666354685401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 15403736139 + ... + 15403737999.

Almost surely, 2^{28666354685409} is an apocalyptic number.

28666354685409 is the 5354097-th square number.

28666354685409 is the 2677049-th centered octagonal number.

It is an amenable number.

28666354685409 is a deficient number, since it is larger than the sum of its proper divisors (19881160615512).

28666354685409 is an frugal number, since it uses more digits than its factorization.

28666354685409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4016 (or 2008 counting only the distinct ones).

The product of its (nonzero) digits is 1791590400, while the sum is 72.

The spelling of 28666354685409 in words is "twenty-eight trillion, six hundred sixty-six billion, three hundred fifty-four million, six hundred eighty-five thousand, four hundred nine".