28721687 has 24 divisors (see below), whose sum is σ = 33156000. Its totient is φ = 24797696.

The previous prime is 28721669. The next prime is 28721699. The reversal of 28721687 is 78612782.

It is not a de Polignac number, because 28721687 - 2¹⁶ = 28656151 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28721617) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 192689 + ... + 192837.

It is an arithmetic number, because the mean of its divisors is an integer number (1381500).

Almost surely, 2^28721687 is an apocalyptic number.

28721687 is a deficient number, since it is larger than the sum of its proper divisors (4434313).

28721687 is a wasteful number, since it uses less digits than its factorization.

28721687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 235 (or 218 counting only the distinct ones).

The product of its digits is 75264, while the sum is 41.

The square root of 28721687 is about 5359.2617961805. The cubic root of 28721687 is about 306.2456874584.

The spelling of 28721687 in words is "twenty-eight million, seven hundred twenty-one thousand, six hundred eighty-seven".