28640520 has 128 divisors (see below), whose sum is σ = 99705600. Its totient is φ = 7299072.

The previous prime is 28640519. The next prime is 28640527. The reversal of 28640520 is 2504682.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (28640527) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 24264 + ... + 25416.

It is an arithmetic number, because the mean of its divisors is an integer number (778950).

Almost surely, 2^28640520 is an apocalyptic number.

28640520 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 28640520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49852800).

28640520 is an abundant number, since it is smaller than the sum of its proper divisors (71065080).

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

28640520 is a wasteful number, since it uses less digits than its factorization.

28640520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1196 (or 1186 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 28640520 is about 5351.6838471644. The cubic root of 28640520 is about 305.9569335777.

The spelling of 28640520 in words is "twenty-eight million, six hundred forty thousand, five hundred twenty".