28391540 has 24 divisors (see below), whose sum is σ = 59808672. Its totient is φ = 11321120.

The previous prime is 28391537. The next prime is 28391563. The reversal of 28391540 is 4519382.

It is a junction number, because it is equal to n+sod(n) for n = 28391497 and 28391506.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4895 + ... + 8985.

It is an arithmetic number, because the mean of its divisors is an integer number (2492028).

Almost surely, 2^28391540 is an apocalyptic number.

28391540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28391540 is an abundant number, since it is smaller than the sum of its proper divisors (31417132).

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

28391540 is a wasteful number, since it uses less digits than its factorization.

28391540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4447 (or 4445 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 28391540 is about 5328.3712333132. The cubic root of 28391540 is about 305.0677624232.

The spelling of 28391540 in words is "twenty-eight million, three hundred ninety-one thousand, five hundred forty".