28278681 has 12 divisors (see below), whose sum is σ = 38272752. Its totient is φ = 18570048.

The previous prime is 28278673. The next prime is 28278697. The reversal of 28278681 is 18687282.

It is not a de Polignac number, because 28278681 - 2³ = 28278673 is a prime.

It is a super-2 number, since 2×28278681² = 1599367598199522, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28278671) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 83745 + ... + 84081.

It is an arithmetic number, because the mean of its divisors is an integer number (3189396).

Almost surely, 2^28278681 is an apocalyptic number.

It is an amenable number.

28278681 is a deficient number, since it is larger than the sum of its proper divisors (9994071).

28278681 is an frugal number, since it uses more digits than its factorization.

28278681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 760 (or 423 counting only the distinct ones).

The product of its digits is 86016, while the sum is 42.

The square root of 28278681 is about 5317.7703034261. The cubic root of 28278681 is about 304.6630014280.

The spelling of 28278681 in words is "twenty-eight million, two hundred seventy-eight thousand, six hundred eighty-one".