28000081 has 8 divisors (see below), whose sum is σ = 28465344. Its totient is φ = 27538800.

The previous prime is 28000073. The next prime is 28000087. The reversal of 28000081 is 18000082.

28000081 = T₄₃₁₉ + T₄₃₂₀ + T₄₃₂₁.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28000081 - 2³ = 28000073 is a prime.

It is a super-2 number, since 2×28000081² = 1568009072013122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28000087) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15291 + ... + 17023.

It is an arithmetic number, because the mean of its divisors is an integer number (3558168).

Almost surely, 2^28000081 is an apocalyptic number.

28000081 is the 4321-st centered triangular number.

It is an amenable number.

28000081 is a deficient number, since it is larger than the sum of its proper divisors (465263).

28000081 is a wasteful number, since it uses less digits than its factorization.

28000081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1991.

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 28000081 is about 5291.5102759042. The cubic root of 28000081 is about 303.6591900012.

Subtracting from 28000081 its reverse (18000082), we obtain a palindrome (9999999).

The spelling of 28000081 in words is "twenty-eight million, eighty-one", and thus it is an aban number and an uban number.