28720275 has 24 divisors (see below), whose sum is σ = 47638320. Its totient is φ = 15267840.

The previous prime is 28720273. The next prime is 28720297. The reversal of 28720275 is 57202782.

It is not a de Polignac number, because 28720275 - 2¹ = 28720273 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28720271) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 42339 + ... + 43011.

It is an arithmetic number, because the mean of its divisors is an integer number (1984930).

Almost surely, 2^28720275 is an apocalyptic number.

28720275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

28720275 is a deficient number, since it is larger than the sum of its proper divisors (18918045).

28720275 is a wasteful number, since it uses less digits than its factorization.

28720275 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1255 (or 1250 counting only the distinct ones).

The product of its (nonzero) digits is 15680, while the sum is 33.

The square root of 28720275 is about 5359.1300600004. The cubic root of 28720275 is about 306.2406688813.

The spelling of 28720275 in words is "twenty-eight million, seven hundred twenty thousand, two hundred seventy-five".