28387440 has 120 divisors (see below), whose sum is σ = 96623280. Its totient is φ = 7468032.

The previous prime is 28387423. The next prime is 28387441. The reversal of 28387440 is 4478382.

It is a tau number, because it is divible by the number of its divisors (120).

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 = 28387395 and 28387404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28387441) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 63859 + ... + 64301.

It is an arithmetic number, because the mean of its divisors is an integer number (805194).

Almost surely, 2^28387440 is an apocalyptic number.

28387440 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 28387440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48311640).

28387440 is an abundant number, since it is smaller than the sum of its proper divisors (68235840).

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

28387440 is a wasteful number, since it uses less digits than its factorization.

28387440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 551 (or 542 counting only the distinct ones).

The product of its (nonzero) digits is 43008, while the sum is 36.

The square root of 28387440 is about 5327.9864864693. The cubic root of 28387440 is about 305.0530768509.

The spelling of 28387440 in words is "twenty-eight million, three hundred eighty-seven thousand, four hundred forty".