28478389 has 4 divisors (see below), whose sum is σ = 28496556. Its totient is φ = 28460224.

The previous prime is 28478339. The next prime is 28478413. The reversal of 28478389 is 98387482.

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

It can be written as a sum of positive squares in 2 ways, for example, as 22515025 + 5963364 = 4745^2 + 2442^2 .

It is a cyclic number.

It is not a de Polignac number, because 28478389 - 2²¹ = 26381237 is a prime.

It is a super-2 number, since 2×28478389² = 1622037280070642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28478339) 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, 6484 + ... + 9949.

It is an arithmetic number, because the mean of its divisors is an integer number (7124139).

Almost surely, 2^28478389 is an apocalyptic number.

It is an amenable number.

28478389 is a deficient number, since it is larger than the sum of its proper divisors (18167).

28478389 is a wasteful number, since it uses less digits than its factorization.

28478389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18166.

The product of its digits is 774144, while the sum is 49.

The square root of 28478389 is about 5336.5146865721. The cubic root of 28478389 is about 305.3785106278.

It can be divided in two parts, 2847 and 8389, that added together give a square (11236 = 106²).

The spelling of 28478389 in words is "twenty-eight million, four hundred seventy-eight thousand, three hundred eighty-nine".