28280881 has 8 divisors (see below), whose sum is σ = 28937384. Its totient is φ = 27630720.

The previous prime is 28280867. The next prime is 28280893. The reversal of 28280881 is 18808282.

It can be written as a sum of positive squares in 4 ways, for example, as 665856 + 27615025 = 816^2 + 5255^2 .

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 28280881 - 2⁷ = 28280753 is a prime.

It is a super-2 number, since 2×28280881² = 1599616460272322, which 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 28280881.

It is not an unprimeable number, because it can be changed into a prime (28280831) 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, 8101 + ... + 11053.

It is an arithmetic number, because the mean of its divisors is an integer number (3617173).

Almost surely, 2^28280881 is an apocalyptic number.

It is an amenable number.

28280881 is a deficient number, since it is larger than the sum of its proper divisors (656503).

28280881 is a wasteful number, since it uses less digits than its factorization.

28280881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3171.

The product of its (nonzero) digits is 16384, while the sum is 37.

The square root of 28280881 is about 5317.9771530160. The cubic root of 28280881 is about 304.6709018580.

It can be divided in two parts, 28280 and 881, that added together give a triangular number (29161 = T₂₄₁).

The spelling of 28280881 in words is "twenty-eight million, two hundred eighty thousand, eight hundred eighty-one".