28400040 has 48 divisors (see below), whose sum is σ = 92301300. Its totient is φ = 7573248.

The previous prime is 28400039. The next prime is 28400051. The reversal of 28400040 is 4000482.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 23444964 + 4955076 = 4842^2 + 2226^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 28399986 and 28400022.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39085 + ... + 39804.

Almost surely, 2^28400040 is an apocalyptic number.

28400040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28400040 is an abundant number, since it is smaller than the sum of its proper divisors (63901260).

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

28400040 is a wasteful number, since it uses less digits than its factorization.

28400040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78906 (or 78899 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 28400040 is about 5329.1687907215. The cubic root of 28400040 is about 305.0982036185.

The spelling of 28400040 in words is "twenty-eight million, four hundred thousand, forty".