28965681 has 20 divisors (see below), whose sum is σ = 43415284. Its totient is φ = 19245600.

The previous prime is 28965679. The next prime is 28965683. The reversal of 28965681 is 18656982.

28965681 is a `hidden beast` number, since 2 + 89 + 6 + 568 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (28965679) and next prime (28965683).

It can be written as a sum of positive squares in 2 ways, for example, as 17514225 + 11451456 = 4185^2 + 3384^2 .

It is not a de Polignac number, because 28965681 - 2¹ = 28965679 is a prime.

It is a super-2 number, since 2×28965681² = 1678021351587522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28965683) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 43491 + ... + 44151.

Almost surely, 2^28965681 is an apocalyptic number.

It is an amenable number.

28965681 is a deficient number, since it is larger than the sum of its proper divisors (14449603).

28965681 is an equidigital number, since it uses as much as digits as its factorization.

28965681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1214 (or 1205 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The square root of 28965681 is about 5381.9774247018. The cubic root of 28965681 is about 307.1104406593.

It can be divided in two parts, 28965 and 681, that added together give a triangular number (29646 = T₂₄₃).

The spelling of 28965681 in words is "twenty-eight million, nine hundred sixty-five thousand, six hundred eighty-one".