28403840 has 32 divisors (see below), whose sum is σ = 67904460. Its totient is φ = 11361280.

The previous prime is 28403833. The next prime is 28403849. The reversal of 28403840 is 4830482.

It can be written as a sum of positive squares in 2 ways, for example, as 27962944 + 440896 = 5288^2 + 664^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (28403849) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21551 + ... + 22830.

Almost surely, 2^28403840 is an apocalyptic number.

28403840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28403840 is an abundant number, since it is smaller than the sum of its proper divisors (39500620).

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

28403840 is an equidigital number, since it uses as much as digits as its factorization.

28403840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44400 (or 44388 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 29.

The square root of 28403840 is about 5329.5253071920. The cubic root of 28403840 is about 305.1118106588. Note that the first 3 decimals are identical.

The spelling of 28403840 in words is "twenty-eight million, four hundred three thousand, eight hundred forty".