28931904 has 70 divisors (see below), whose sum is σ = 85778594. Its totient is φ = 9642240.

The previous prime is 28931869. The next prime is 28931911. The reversal of 28931904 is 40913982.

It can be written as a sum of positive squares in only one way, i.e., 22581504 + 6350400 = 4752^2 + 2520^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nialpdrome in base 12.

It is a congruent number.

It is an unprimeable number.

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 9 ways as a sum of consecutive naturals, for example, 2394 + ... + 7974.

Almost surely, 2^28931904 is an apocalyptic number.

28931904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28931904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42889297).

28931904 is an abundant number, since it is smaller than the sum of its proper divisors (56846690).

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

28931904 is an equidigital number, since it uses as much as digits as its factorization.

28931904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5605 (or 5586 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 28931904 is about 5378.8385363385. The cubic root of 28931904 is about 306.9910199780.

The spelling of 28931904 in words is "twenty-eight million, nine hundred thirty-one thousand, nine hundred four".