28391975 has 12 divisors (see below), whose sum is σ = 35339256. Its totient is φ = 22627680.

The previous prime is 28391971. The next prime is 28391981. The reversal of 28391975 is 57919382.

It is not a de Polignac number, because 28391975 - 2² = 28391971 is a prime.

It is a super-2 number, since 2×28391975² = 1612208488801250, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28391971) 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 11 ways as a sum of consecutive naturals, for example, 5069 + ... + 9081.

It is an arithmetic number, because the mean of its divisors is an integer number (2944938).

Almost surely, 2^28391975 is an apocalyptic number.

28391975 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

28391975 is a deficient number, since it is larger than the sum of its proper divisors (6947281).

28391975 is a wasteful number, since it uses less digits than its factorization.

28391975 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4306 (or 4301 counting only the distinct ones).

The product of its digits is 136080, while the sum is 44.

The square root of 28391975 is about 5328.4120523848. The cubic root of 28391975 is about 305.0693204436.

The spelling of 28391975 in words is "twenty-eight million, three hundred ninety-one thousand, nine hundred seventy-five".