28331729 has 4 divisors (see below), whose sum is σ = 28360500. Its totient is φ = 28302960.

The previous prime is 28331701. The next prime is 28331747. The reversal of 28331729 is 92713382.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11888704 + 16443025 = 3448^2 + 4055^2 .

It is a cyclic number.

It is not a de Polignac number, because 28331729 - 2¹² = 28327633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28331759) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12854 + ... + 14895.

It is an arithmetic number, because the mean of its divisors is an integer number (7090125).

Almost surely, 2^28331729 is an apocalyptic number.

It is an amenable number.

28331729 is a deficient number, since it is larger than the sum of its proper divisors (28771).

28331729 is a wasteful number, since it uses less digits than its factorization.

28331729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28770.

The product of its digits is 18144, while the sum is 35.

The square root of 28331729 is about 5322.7557712148. The cubic root of 28331729 is about 304.8533882835.

The spelling of 28331729 in words is "twenty-eight million, three hundred thirty-one thousand, seven hundred twenty-nine".