28731540 has 48 divisors (see below), whose sum is σ = 80720640. Its totient is φ = 7635840.

The previous prime is 28731517. The next prime is 28731551. The reversal of 28731540 is 4513782.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 28731498 and 28731507.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22725 + ... + 23955.

It is an arithmetic number, because the mean of its divisors is an integer number (1681680).

Almost surely, 2^28731540 is an apocalyptic number.

28731540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28731540 is an abundant number, since it is smaller than the sum of its proper divisors (51989100).

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

28731540 is a wasteful number, since it uses less digits than its factorization.

28731540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1632 (or 1630 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 30.

The square root of 28731540 is about 5360.1809670943. The cubic root of 28731540 is about 306.2807027389.

The spelling of 28731540 in words is "twenty-eight million, seven hundred thirty-one thousand, five hundred forty".