28279440 has 240 divisors, whose sum is σ = 112659456. Its totient is φ = 6220800.

The previous prime is 28279399. The next prime is 28279441. The reversal of 28279440 is 4497282.

It is a tau number, because it is divible by the number of its divisors (240).

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

It is a junction number, because it is equal to n+sod(n) for n = 28279395 and 28279404.

It is not an unprimeable number, because it can be changed into a prime (28279441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 156150 + ... + 156330.

Almost surely, 2^28279440 is an apocalyptic number.

28279440 is a gapful number since it is divisible by the number (20) 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 28279440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (56329728).

28279440 is an abundant number, since it is smaller than the sum of its proper divisors (84380016).

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

28279440 is a wasteful number, since it uses less digits than its factorization.

28279440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238 (or 229 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The square root of 28279440 is about 5317.8416674437. The cubic root of 28279440 is about 304.6657271227.

The spelling of 28279440 in words is "twenty-eight million, two hundred seventy-nine thousand, four hundred forty".