28991520 has 120 divisors (see below), whose sum is σ = 102361644. Its totient is φ = 7727616.

The previous prime is 28991519. The next prime is 28991563. The reversal of 28991520 is 2519982.

It can be written as a sum of positive squares in 2 ways, for example, as 28772496 + 219024 = 5364^2 + 468^2 .

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 11842 + ... + 14078.

Almost surely, 2^28991520 is an apocalyptic number.

28991520 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 28991520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (51180822).

28991520 is an abundant number, since it is smaller than the sum of its proper divisors (73370124).

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

28991520 is a wasteful number, since it uses less digits than its factorization.

28991520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2264 (or 2247 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 28991520 is about 5384.3774013343. The cubic root of 28991520 is about 307.2017333887.

It can be divided in two parts, 289 and 91520, that added together give a square (91809 = 303²).

The spelling of 28991520 in words is "twenty-eight million, nine hundred ninety-one thousand, five hundred twenty".