28125831409 has 4 divisors (see below), whose sum is σ = 30289356916. Its totient is φ = 25962305904.

The previous prime is 28125831401. The next prime is 28125831421. The reversal of 28125831409 is 90413852182.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90413852182 = 2 ⋅45206926091.

It can be written as a sum of positive squares in 2 ways, for example, as 9019680784 + 19106150625 = 94972^2 + 138225^2 .

It is a cyclic number.

It is not a de Polignac number, because 28125831409 - 2³ = 28125831401 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28125831401) 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, 1081762734 + ... + 1081762759.

It is an arithmetic number, because the mean of its divisors is an integer number (7572339229).

Almost surely, 2^28125831409 is an apocalyptic number.

It is an amenable number.

28125831409 is a deficient number, since it is larger than the sum of its proper divisors (2163525507).

28125831409 is a wasteful number, since it uses less digits than its factorization.

28125831409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2163525506.

The product of its (nonzero) digits is 138240, while the sum is 43.

The spelling of 28125831409 in words is "twenty-eight billion, one hundred twenty-five million, eight hundred thirty-one thousand, four hundred nine".