28809788581 has 6 divisors (see below), whose sum is σ = 33513427590. Its totient is φ = 24694104456.

The previous prime is 28809788561. The next prime is 28809788587. The reversal of 28809788581 is 18588790882.

It can be written as a sum of positive squares in only one way, i.e., 26715902500 + 2093886081 = 163450^2 + 45759^2 .

It is not a de Polignac number, because 28809788581 - 2⁵ = 28809788549 is a prime.

It is a super-2 number, since 2×28809788581² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28809788587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 293977386 + ... + 293977483.

It is an arithmetic number, because the mean of its divisors is an integer number (5585571265).

Almost surely, 2^28809788581 is an apocalyptic number.

It is an amenable number.

28809788581 is a deficient number, since it is larger than the sum of its proper divisors (4703639009).

28809788581 is an equidigital number, since it uses as much as digits as its factorization.

28809788581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 587954883 (or 587954876 counting only the distinct ones).

The product of its (nonzero) digits is 20643840, while the sum is 64.

The spelling of 28809788581 in words is "twenty-eight billion, eight hundred nine million, seven hundred eighty-eight thousand, five hundred eighty-one".