28447821 has 16 divisors (see below), whose sum is σ = 42681600. Its totient is φ = 18723744.

The previous prime is 28447819. The next prime is 28447823. The reversal of 28447821 is 12874482.

It is an interprime number because it is at equal distance from previous prime (28447819) and next prime (28447823).

It is not a de Polignac number, because 28447821 - 2¹ = 28447819 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

28447821 is a modest number, since divided by 7821 gives 2844 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28447823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4536 + ... + 8801.

It is an arithmetic number, because the mean of its divisors is an integer number (2667600).

Almost surely, 2^28447821 is an apocalyptic number.

It is an amenable number.

28447821 is a deficient number, since it is larger than the sum of its proper divisors (14233779).

28447821 is a wasteful number, since it uses less digits than its factorization.

28447821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13425 (or 13419 counting only the distinct ones).

The product of its digits is 28672, while the sum is 36.

The square root of 28447821 is about 5333.6498760230. The cubic root of 28447821 is about 305.2692095923.

The spelling of 28447821 in words is "twenty-eight million, four hundred forty-seven thousand, eight hundred twenty-one".