28889681 has 4 divisors (see below), whose sum is σ = 30589092. Its totient is φ = 27190272.

The previous prime is 28889639. The next prime is 28889683. The reversal of 28889681 is 18698882.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10784656 + 18105025 = 3284^2 + 4255^2 .

It is a cyclic number.

It is not a de Polignac number, because 28889681 - 2⁶ = 28889617 is a prime.

It is a super-2 number, since 2×28889681² = 1669227336563522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28889683) 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, 849680 + ... + 849713.

It is an arithmetic number, because the mean of its divisors is an integer number (7647273).

Almost surely, 2^28889681 is an apocalyptic number.

It is an amenable number.

28889681 is a deficient number, since it is larger than the sum of its proper divisors (1699411).

28889681 is a wasteful number, since it uses less digits than its factorization.

28889681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1699410.

The product of its digits is 442368, while the sum is 50.

The square root of 28889681 is about 5374.9121853292. The cubic root of 28889681 is about 306.8416071529.

The spelling of 28889681 in words is "twenty-eight million, eight hundred eighty-nine thousand, six hundred eighty-one".