28915440 has 80 divisors (see below), whose sum is σ = 90220416. Its totient is φ = 7660800.

The previous prime is 28915427. The next prime is 28915441. The reversal of 28915440 is 4451982.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×28915440² = 1672205340787200, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28915441) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50355 + ... + 50925.

Almost surely, 2^28915440 is an apocalyptic number.

28915440 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 28915440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45110208).

28915440 is an abundant number, since it is smaller than the sum of its proper divisors (61304976).

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

28915440 is a wasteful number, since it uses less digits than its factorization.

28915440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 798 (or 792 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 33.

The square root of 28915440 is about 5377.3078766238. The cubic root of 28915440 is about 306.9327767875.

The spelling of 28915440 in words is "twenty-eight million, nine hundred fifteen thousand, four hundred forty".