28990109 has 4 divisors (see below), whose sum is σ = 29003580. Its totient is φ = 28976640.

The previous prime is 28990061. The next prime is 28990133. The reversal of 28990109 is 90109982.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90109982 = 2 ⋅45054991.

It can be written as a sum of positive squares in 2 ways, for example, as 3960100 + 25030009 = 1990^2 + 5003^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28990109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28990139) 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, 2702 + ... + 8079.

It is an arithmetic number, because the mean of its divisors is an integer number (7250895).

Almost surely, 2^28990109 is an apocalyptic number.

It is an amenable number.

28990109 is a deficient number, since it is larger than the sum of its proper divisors (13471).

28990109 is a wasteful number, since it uses less digits than its factorization.

28990109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13470.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 28990109 is about 5384.2463725205. The cubic root of 28990109 is about 307.1967495327.

The spelling of 28990109 in words is "twenty-eight million, nine hundred ninety thousand, one hundred nine".