28405440 has 168 divisors, whose sum is σ = 111739680. Its totient is φ = 6488064.

The previous prime is 28405423. The next prime is 28405451. The reversal of 28405440 is 4450482.

It is a tau number, because it is divible by the number of its divisors (168).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19456 + ... + 20864.

Almost surely, 2^28405440 is an apocalyptic number.

28405440 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 28405440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (55869840).

28405440 is an abundant number, since it is smaller than the sum of its proper divisors (83334240).

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

28405440 is a wasteful number, since it uses less digits than its factorization.

28405440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1439 (or 1426 counting only the distinct ones).

The product of its (nonzero) digits is 5120, while the sum is 27.

The square root of 28405440 is about 5329.6754122554. The cubic root of 28405440 is about 305.1175395759.

The spelling of 28405440 in words is "twenty-eight million, four hundred five thousand, four hundred forty".