28644640 has 24 divisors (see below), whose sum is σ = 67673340. Its totient is φ = 11457792.

The previous prime is 28644619. The next prime is 28644641. The reversal of 28644640 is 4644682.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 26173456 + 2471184 = 5116^2 + 1572^2 .

It is a junction number, because it is equal to n+sod(n) for n = 28644596 and 28644605.

It is not an unprimeable number, because it can be changed into a prime (28644641) 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, 89355 + ... + 89674.

Almost surely, 2^28644640 is an apocalyptic number.

28644640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28644640 is an abundant number, since it is smaller than the sum of its proper divisors (39028700).

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

28644640 is a wasteful number, since it uses less digits than its factorization.

28644640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179044 (or 179036 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 34.

The square root of 28644640 is about 5352.0687589006. The cubic root of 28644640 is about 305.9716037272.

The spelling of 28644640 in words is "twenty-eight million, six hundred forty-four thousand, six hundred forty".