28139278 has 4 divisors (see below), whose sum is σ = 42208920. Its totient is φ = 14069638.

The previous prime is 28139269. The next prime is 28139297. The reversal of 28139278 is 87293182.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×28139278² = 1583637932722568, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 28139278.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7034818 + ... + 7034821.

It is an arithmetic number, because the mean of its divisors is an integer number (10552230).

Almost surely, 2^28139278 is an apocalyptic number.

28139278 is a deficient number, since it is larger than the sum of its proper divisors (14069642).

28139278 is a wasteful number, since it uses less digits than its factorization.

28139278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14069641.

The product of its digits is 48384, while the sum is 40.

The square root of 28139278 is about 5304.6468308456. The cubic root of 28139278 is about 304.1615528091.

The spelling of 28139278 in words is "twenty-eight million, one hundred thirty-nine thousand, two hundred seventy-eight".