28720706 has 8 divisors (see below), whose sum is σ = 49235520. Its totient is φ = 12308868.

The previous prime is 28720673. The next prime is 28720709. The reversal of 28720706 is 60702782.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28720709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1025726 + ... + 1025753.

It is an arithmetic number, because the mean of its divisors is an integer number (6154440).

Almost surely, 2^28720706 is an apocalyptic number.

28720706 is a deficient number, since it is larger than the sum of its proper divisors (20514814).

28720706 is a wasteful number, since it uses less digits than its factorization.

28720706 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2051488.

The product of its (nonzero) digits is 9408, while the sum is 32.

The square root of 28720706 is about 5359.1702715999. The cubic root of 28720706 is about 306.2422007732.

The spelling of 28720706 in words is "twenty-eight million, seven hundred twenty thousand, seven hundred six".