28757378761 has 4 divisors (see below), whose sum is σ = 29534605252. Its totient is φ = 27980152272.

The previous prime is 28757378747. The next prime is 28757378777. The reversal of 28757378761 is 16787375782.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16787375782 = 2 ⋅8393687891.

It can be written as a sum of positive squares in 2 ways, for example, as 25963199161 + 2794179600 = 161131^2 + 52860^2 .

It is a cyclic number.

It is not a de Polignac number, because 28757378761 - 2¹³ = 28757370569 is a prime.

It is a super-2 number, since 2×28757378761² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28757378761.

It is not an unprimeable number, because it can be changed into a prime (28757378861) 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, 388613190 + ... + 388613263.

It is an arithmetic number, because the mean of its divisors is an integer number (7383651313).

Almost surely, 2^28757378761 is an apocalyptic number.

It is an amenable number.

28757378761 is a deficient number, since it is larger than the sum of its proper divisors (777226491).

28757378761 is an equidigital number, since it uses as much as digits as its factorization.

28757378761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 777226490.

The product of its digits is 27659520, while the sum is 61.

The spelling of 28757378761 in words is "twenty-eight billion, seven hundred fifty-seven million, three hundred seventy-eight thousand, seven hundred sixty-one".