28278725 has 24 divisors (see below), whose sum is σ = 36747648. Its totient is φ = 21564800.

The previous prime is 28278713. The next prime is 28278739. The reversal of 28278725 is 52787282.

It is a happy number.

It is not a de Polignac number, because 28278725 - 2¹⁶ = 28213189 is a prime.

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 47882 + ... + 48468.

It is an arithmetic number, because the mean of its divisors is an integer number (1531152).

Almost surely, 2^28278725 is an apocalyptic number.

28278725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

28278725 is a deficient number, since it is larger than the sum of its proper divisors (8468923).

28278725 is a wasteful number, since it uses less digits than its factorization.

28278725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 685 (or 680 counting only the distinct ones).

The product of its digits is 125440, while the sum is 41.

The square root of 28278725 is about 5317.7744404967. The cubic root of 28278725 is about 304.6631594406.

28278725 divided by its sum of digits (41) gives a triangular number (689725 = T₁₁₇₄).

The spelling of 28278725 in words is "twenty-eight million, two hundred seventy-eight thousand, seven hundred twenty-five".