28127820409 has 4 divisors (see below), whose sum is σ = 30291498916. Its totient is φ = 25964141904.

The previous prime is 28127820379. The next prime is 28127820443. The reversal of 28127820409 is 90402872182.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10480026384 + 17647794025 = 102372^2 + 132845^2 .

It is a cyclic number.

It is not a de Polignac number, because 28127820409 - 2¹⁹ = 28127296121 is a prime.

It is a super-3 number, since 3×28127820409³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28127820499) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1081839234 + ... + 1081839259.

It is an arithmetic number, because the mean of its divisors is an integer number (7572874729).

Almost surely, 2^28127820409 is an apocalyptic number.

It is an amenable number.

28127820409 is a deficient number, since it is larger than the sum of its proper divisors (2163678507).

28127820409 is a wasteful number, since it uses less digits than its factorization.

28127820409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2163678506.

The product of its (nonzero) digits is 129024, while the sum is 43.

The spelling of 28127820409 in words is "twenty-eight billion, one hundred twenty-seven million, eight hundred twenty thousand, four hundred nine".