28443381 has 16 divisors (see below), whose sum is σ = 39408768. Its totient is φ = 18233600.

The previous prime is 28443379. The next prime is 28443439. The reversal of 28443381 is 18334482.

It is a cyclic number.

It is not a de Polignac number, because 28443381 - 2¹ = 28443379 is a prime.

It is a super-2 number, since 2×28443381² = 1618051845422322, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28443281) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7105 + ... + 10361.

It is an arithmetic number, because the mean of its divisors is an integer number (2463048).

Almost surely, 2^28443381 is an apocalyptic number.

It is an amenable number.

28443381 is a deficient number, since it is larger than the sum of its proper divisors (10965387).

28443381 is a wasteful number, since it uses less digits than its factorization.

28443381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3372.

The product of its digits is 18432, while the sum is 33.

The square root of 28443381 is about 5333.2336344848. The cubic root of 28443381 is about 305.2533271126.

The spelling of 28443381 in words is "twenty-eight million, four hundred forty-three thousand, three hundred eighty-one".