28718881 has 9 divisors (see below), whose sum is σ = 30151219. Its totient is φ = 27352336.

The previous prime is 28718873. The next prime is 28718897. The reversal of 28718881 is 18881782.

The square root of 28718881 is 5359.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 5832225 + 22886656 = 2415^2 + 4784^2 .

It is not a de Polignac number, because 28718881 - 2³ = 28718873 is a prime.

It is a super-2 number, since 2×28718881² = 1649548251784322, which contains 22 as substring.

It is a Duffinian number.

Its product of digits (57344) is a multiple of the sum of its prime divisors (256).

It is not an unprimeable number, because it can be changed into a prime (28718801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 123141 + ... + 123373.

Almost surely, 2^28718881 is an apocalyptic number.

28718881 is the 5359-th square number.

28718881 is the 2680-th centered octagonal number.

It is an amenable number.

28718881 is a deficient number, since it is larger than the sum of its proper divisors (1432338).

28718881 is an frugal number, since it uses more digits than its factorization.

28718881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 512 (or 256 counting only the distinct ones).

The product of its digits is 57344, while the sum is 43.

The cubic root of 28718881 is about 306.2357141191.

The spelling of 28718881 in words is "twenty-eight million, seven hundred eighteen thousand, eight hundred eighty-one".