28728729 has 16 divisors (see below), whose sum is σ = 43199040. Its totient is φ = 18865440.

The previous prime is 28728727. The next prime is 28728731. The reversal of 28728729 is 92782782.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (28728727) and next prime (28728731).

It is not a de Polignac number, because 28728729 - 2¹ = 28728727 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (28728727) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6132 + ... + 9749.

It is an arithmetic number, because the mean of its divisors is an integer number (2699940).

Almost surely, 2^28728729 is an apocalyptic number.

It is an amenable number.

28728729 is a deficient number, since it is larger than the sum of its proper divisors (14470311).

28728729 is a wasteful number, since it uses less digits than its factorization.

28728729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15957 (or 15951 counting only the distinct ones).

The product of its digits is 225792, while the sum is 45.

The square root of 28728729 is about 5359.9187493842. The cubic root of 28728729 is about 306.2707139120.

The spelling of 28728729 in words is "twenty-eight million, seven hundred twenty-eight thousand, seven hundred twenty-nine".