28722691 has 4 divisors (see below), whose sum is σ = 28742112. Its totient is φ = 28703272.

The previous prime is 28722689. The next prime is 28722721. The reversal of 28722691 is 19622782.

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

It is a cyclic number.

It is not a de Polignac number, because 28722691 - 2¹ = 28722689 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28722691.

It is not an unprimeable number, because it can be changed into a prime (28722601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7291 + ... + 10516.

It is an arithmetic number, because the mean of its divisors is an integer number (7185528).

Almost surely, 2^28722691 is an apocalyptic number.

28722691 is a deficient number, since it is larger than the sum of its proper divisors (19421).

28722691 is a wasteful number, since it uses less digits than its factorization.

28722691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19420.

The product of its digits is 24192, while the sum is 37.

The square root of 28722691 is about 5359.3554649790. The cubic root of 28722691 is about 306.2492558083.

Subtracting from 28722691 its reverse (19622782), we obtain a palindrome (9099909).

The spelling of 28722691 in words is "twenty-eight million, seven hundred twenty-two thousand, six hundred ninety-one".