28171904 has 32 divisors (see below), whose sum is σ = 56727300. Its totient is φ = 13934592.

The previous prime is 28171903. The next prime is 28171909. The reversal of 28171904 is 40917182.

28171904 = T₄₃₉ + T₄₄₀ + ... + T₆₃₂.

It can be written as a sum of positive squares in 2 ways, for example, as 25482304 + 2689600 = 5048^2 + 1640^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is not an unprimeable number, because it can be changed into a prime (28171903) 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 3 ways as a sum of consecutive naturals, for example, 11282 + ... + 13550.

Almost surely, 2^28171904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28171904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28363650).

28171904 is an abundant number, since it is smaller than the sum of its proper divisors (28555396).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28171904 is an equidigital number, since it uses as much as digits as its factorization.

28171904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2380 (or 2368 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 28171904 is about 5307.7211682604. The cubic root of 28171904 is about 304.2790604675.

The spelling of 28171904 in words is "twenty-eight million, one hundred seventy-one thousand, nine hundred four".