28820551 has 4 divisors (see below), whose sum is σ = 28863432. Its totient is φ = 28777672.

The previous prime is 28820531. The next prime is 28820569. The reversal of 28820551 is 15502882.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15502882 = 2 ⋅7751441.

It is a cyclic number.

It is not a de Polignac number, because 28820551 - 2⁹ = 28820039 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 (28820531) 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, 20416 + ... + 21781.

It is an arithmetic number, because the mean of its divisors is an integer number (7215858).

Almost surely, 2^28820551 is an apocalyptic number.

28820551 is a deficient number, since it is larger than the sum of its proper divisors (42881).

28820551 is an equidigital number, since it uses as much as digits as its factorization.

28820551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42880.

The product of its (nonzero) digits is 6400, while the sum is 31.

The square root of 28820551 is about 5368.4775309207. The cubic root of 28820551 is about 306.5966649978.

The spelling of 28820551 in words is "twenty-eight million, eight hundred twenty thousand, five hundred fifty-one".