28444221 has 18 divisors (see below), whose sum is σ = 44492058. Its totient is φ = 17503200.

The previous prime is 28444219. The next prime is 28444223. The reversal of 28444221 is 12244482.

It is an interprime number because it is at equal distance from previous prime (28444219) and next prime (28444223).

It can be written as a sum of positive squares in 3 ways, for example, as 881721 + 27562500 = 939^2 + 5250^2 .

It is not a de Polignac number, because 28444221 - 2¹ = 28444219 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28444223) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 7830 + ... + 10871.

It is an arithmetic number, because the mean of its divisors is an integer number (2471781).

Almost surely, 2^28444221 is an apocalyptic number.

It is an amenable number.

28444221 is a deficient number, since it is larger than the sum of its proper divisors (16047837).

28444221 is a wasteful number, since it uses less digits than its factorization.

28444221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18733 (or 18717 counting only the distinct ones).

The product of its digits is 4096, while the sum is 27.

The square root of 28444221 is about 5333.3123853755. The cubic root of 28444221 is about 305.2563320328.

The spelling of 28444221 in words is "twenty-eight million, four hundred forty-four thousand, two hundred twenty-one".