28473821 has 4 divisors (see below), whose sum is σ = 28487100. Its totient is φ = 28460544.

The previous prime is 28473811. The next prime is 28473829. The reversal of 28473821 is 12837482.

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 2208196 + 26265625 = 1486^2 + 5125^2 .

It is a cyclic number.

It is not a de Polignac number, because 28473821 - 2¹⁰ = 28472797 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 (28473829) 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, 2606 + ... + 7983.

It is an arithmetic number, because the mean of its divisors is an integer number (7121775).

Almost surely, 2^28473821 is an apocalyptic number.

It is an amenable number.

28473821 is a deficient number, since it is larger than the sum of its proper divisors (13279).

28473821 is a wasteful number, since it uses less digits than its factorization.

28473821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13278.

The product of its digits is 21504, while the sum is 35.

The square root of 28473821 is about 5336.0866747083. The cubic root of 28473821 is about 305.3621819463.

The spelling of 28473821 in words is "twenty-eight million, four hundred seventy-three thousand, eight hundred twenty-one".