28997009 has 4 divisors (see below), whose sum is σ = 29208804. Its totient is φ = 28785216.

The previous prime is 28996993. The next prime is 28997027. The reversal of 28997009 is 90079982.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90079982 = 2 ⋅45039991.

It can be written as a sum of positive squares in 2 ways, for example, as 22771984 + 6225025 = 4772^2 + 2495^2 .

It is a cyclic number.

It is not a de Polignac number, because 28997009 - 2⁴ = 28996993 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 (28990009) 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, 105692 + ... + 105965.

It is an arithmetic number, because the mean of its divisors is an integer number (7302201).

Almost surely, 2^28997009 is an apocalyptic number.

It is an amenable number.

28997009 is a deficient number, since it is larger than the sum of its proper divisors (211795).

28997009 is a wasteful number, since it uses less digits than its factorization.

28997009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211794.

The product of its (nonzero) digits is 81648, while the sum is 44.

The square root of 28997009 is about 5384.8870925953. The cubic root of 28997009 is about 307.2211197921.

The spelling of 28997009 in words is "twenty-eight million, nine hundred ninety-seven thousand, nine".