28991040 has 224 divisors, whose sum is σ = 104461056. Its totient is φ = 6758400.

The previous prime is 28991021. The next prime is 28991041. The reversal of 28991040 is 4019982.

It is a junction number, because it is equal to n+sod(n) for n = 28990992 and 28991010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28991041) 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, 286990 + ... + 287090.

It is an arithmetic number, because the mean of its divisors is an integer number (466344).

Almost surely, 2^28991040 is an apocalyptic number.

28991040 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 28991040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (52230528).

28991040 is an abundant number, since it is smaller than the sum of its proper divisors (75470016).

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

28991040 is a wasteful number, since it uses less digits than its factorization.

28991040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157 (or 147 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 33.

The square root of 28991040 is about 5384.3328277513. The cubic root of 28991040 is about 307.2000379774.

The spelling of 28991040 in words is "twenty-eight million, nine hundred ninety-one thousand, forty".