28021069 has 4 divisors (see below), whose sum is σ = 28310044. Its totient is φ = 27732096.

The previous prime is 28021057. The next prime is 28021087. The reversal of 28021069 is 96012082.

It is a happy number.

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 20811844 + 7209225 = 4562^2 + 2685^2 .

It is a cyclic number.

It is not a de Polignac number, because 28021069 - 2¹³ = 28012877 is a prime.

It is a super-2 number, since 2×28021069² = 1570360615805522, 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 (28021009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 144342 + ... + 144535.

It is an arithmetic number, because the mean of its divisors is an integer number (7077511).

Almost surely, 2^28021069 is an apocalyptic number.

It is an amenable number.

28021069 is a deficient number, since it is larger than the sum of its proper divisors (288975).

28021069 is an equidigital number, since it uses as much as digits as its factorization.

28021069 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 288974.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 28021069 is about 5293.4930811327. The cubic root of 28021069 is about 303.7350422503.

The spelling of 28021069 in words is "twenty-eight million, twenty-one thousand, sixty-nine".