28009281 has 8 divisors (see below), whose sum is σ = 38050560. Its totient is φ = 18320432.

The previous prime is 28009231. The next prime is 28009291. The reversal of 28009281 is 18290082.

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 28009281 - 2⁷ = 28009153 is a prime.

It is a super-2 number, since 2×28009281² = 1569039644273922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28009231) 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, 87921 + ... + 88238.

It is an arithmetic number, because the mean of its divisors is an integer number (4756320).

Almost surely, 2^28009281 is an apocalyptic number.

It is an amenable number.

28009281 is a deficient number, since it is larger than the sum of its proper divisors (10041279).

28009281 is a wasteful number, since it uses less digits than its factorization.

28009281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176215.

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 28009281 is about 5292.3795215385. The cubic root of 28009281 is about 303.6924441744.

The spelling of 28009281 in words is "twenty-eight million, nine thousand, two hundred eighty-one".