28720818 has 160 divisors (see below), whose sum is σ = 81776640. Its totient is φ = 7348320.

The previous prime is 28720801. The next prime is 28720819. The reversal of 28720818 is 81802782.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28720819) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 667905 + ... + 667947.

It is an arithmetic number, because the mean of its divisors is an integer number (511104).

Almost surely, 2^28720818 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28720818, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40888320).

28720818 is an abundant number, since it is smaller than the sum of its proper divisors (53055822).

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

28720818 is a wasteful number, since it uses less digits than its factorization.

28720818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114 (or 105 counting only the distinct ones).

The product of its (nonzero) digits is 14336, while the sum is 36.

The square root of 28720818 is about 5359.1807209685. The cubic root of 28720818 is about 306.2425988493.

The spelling of 28720818 in words is "twenty-eight million, seven hundred twenty thousand, eight hundred eighteen".