28538578561 has 4 divisors (see below), whose sum is σ = 28539223300. Its totient is φ = 28537933824.

The previous prime is 28538578547. The next prime is 28538578567. The reversal of 28538578561 is 16587583582.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16587583582 = 2 ⋅8293791791.

It can be written as a sum of positive squares in 2 ways, for example, as 5814825025 + 22723753536 = 76255^2 + 150744^2 .

It is a cyclic number.

It is not a de Polignac number, because 28538578561 - 2⁵ = 28538578529 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28538578496 and 28538578505.

It is not an unprimeable number, because it can be changed into a prime (28538578567) 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, 250656 + ... + 346273.

It is an arithmetic number, because the mean of its divisors is an integer number (7134805825).

Almost surely, 2^28538578561 is an apocalyptic number.

It is an amenable number.

28538578561 is a deficient number, since it is larger than the sum of its proper divisors (644739).

28538578561 is an equidigital number, since it uses as much as digits as its factorization.

28538578561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644738.

The product of its digits is 16128000, while the sum is 58.

The spelling of 28538578561 in words is "twenty-eight billion, five hundred thirty-eight million, five hundred seventy-eight thousand, five hundred sixty-one".