28181664 has 108 divisors (see below), whose sum is σ = 93272634. Its totient is φ = 8047872.

The previous prime is 28181663. The next prime is 28181669. The reversal of 28181664 is 46618182.

It can be written as a sum of positive squares in only one way, i.e., 28005264 + 176400 = 5292^2 + 420^2 .

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

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (28181663) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 13114 + ... + 15110.

Almost surely, 2^28181664 is an apocalyptic number.

28181664 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 28181664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46636317).

28181664 is an abundant number, since it is smaller than the sum of its proper divisors (65090970).

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

28181664 is a wasteful number, since it uses less digits than its factorization.

28181664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2027 (or 2009 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 28181664 is about 5308.6405039332. The cubic root of 28181664 is about 304.3141950085.

The spelling of 28181664 in words is "twenty-eight million, one hundred eighty-one thousand, six hundred sixty-four".