28663689 has 4 divisors (see below), whose sum is σ = 38218256. Its totient is φ = 19109124.

The previous prime is 28663673. The next prime is 28663709. The reversal of 28663689 is 98636682.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 28663689 - 2⁴ = 28663673 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28663639) 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, 4777279 + ... + 4777284.

It is an arithmetic number, because the mean of its divisors is an integer number (9554564).

Almost surely, 2^28663689 is an apocalyptic number.

It is an amenable number.

28663689 is a deficient number, since it is larger than the sum of its proper divisors (9554567).

28663689 is an equidigital number, since it uses as much as digits as its factorization.

28663689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9554566.

The product of its digits is 746496, while the sum is 48.

The square root of 28663689 is about 5353.8480553710. The cubic root of 28663689 is about 306.0394135229.

It can be divided in two parts, 2866 and 3689, that added together give a triangular number (6555 = T₁₁₄).

The spelling of 28663689 in words is "twenty-eight million, six hundred sixty-three thousand, six hundred eighty-nine".