28391280 has 40 divisors (see below), whose sum is σ = 88013712. Its totient is φ = 7570944.

The previous prime is 28391249. The next prime is 28391281. The reversal of 28391280 is 8219382.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28391281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 58909 + ... + 59388.

Almost surely, 2^28391280 is an apocalyptic number.

28391280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28391280 is an abundant number, since it is smaller than the sum of its proper divisors (59622432).

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

28391280 is a wasteful number, since it uses less digits than its factorization.

28391280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118313 (or 118307 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 28391280 is about 5328.3468355579. The cubic root of 28391280 is about 305.0668311849.

The spelling of 28391280 in words is "twenty-eight million, three hundred ninety-one thousand, two hundred eighty".