28388940 has 48 divisors (see below), whose sum is σ = 81188352. Its totient is φ = 7408576.

The previous prime is 28388909. The next prime is 28388947. The reversal of 28388940 is 4988382.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 28388892 and 28388901.

It is not an unprimeable number, because it can be changed into a prime (28388947) 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, 2214 + ... + 7853.

It is an arithmetic number, because the mean of its divisors is an integer number (1691424).

Almost surely, 2^28388940 is an apocalyptic number.

28388940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28388940 is an abundant number, since it is smaller than the sum of its proper divisors (52799412).

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

28388940 is a wasteful number, since it uses less digits than its factorization.

28388940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10126 (or 10124 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 42.

The square root of 28388940 is about 5328.1272507327. The cubic root of 28388940 is about 305.0584497852.

The spelling of 28388940 in words is "twenty-eight million, three hundred eighty-eight thousand, nine hundred forty".