28403640 has 96 divisors (see below), whose sum is σ = 92972880. Its totient is φ = 7520256.

The previous prime is 28403633. The next prime is 28403647. The reversal of 28403640 is 4630482.

It is an interprime number because it is at equal distance from previous prime (28403633) and next prime (28403647).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28403647) 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, 92367 + ... + 92673.

Almost surely, 2^28403640 is an apocalyptic number.

28403640 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 28403640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46486440).

28403640 is an abundant number, since it is smaller than the sum of its proper divisors (64569240).

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

28403640 is a wasteful number, since it uses less digits than its factorization.

28403640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 581 (or 574 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 27.

The square root of 28403640 is about 5329.5065437618. The cubic root of 28403640 is about 305.1110945291. Note that the first 3 decimals are identical.

The spelling of 28403640 in words is "twenty-eight million, four hundred three thousand, six hundred forty".