28011001 has 4 divisors (see below), whose sum is σ = 28022004. Its totient is φ = 28000000.

The previous prime is 28010971. The next prime is 28011023. The reversal of 28011001 is 10011082.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 5400976 + 22610025 = 2324^2 + 4755^2 .

It is a cyclic number.

It is not a de Polignac number, because 28011001 - 2¹³ = 28002809 is a prime.

It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28011031) 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, 501 + ... + 7501.

It is an arithmetic number, because the mean of its divisors is an integer number (7005501).

It is a Poulet number, since it divides 2^28011000-1.

Almost surely, 2^28011001 is an apocalyptic number.

It is an amenable number.

28011001 is a deficient number, since it is larger than the sum of its proper divisors (11003).

28011001 is an equidigital number, since it uses as much as digits as its factorization.

28011001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11002.

The product of its (nonzero) digits is 16, while the sum is 13.

The square root of 28011001 is about 5292.5420168384. The cubic root of 28011001 is about 303.6986604510.

Adding to 28011001 its reverse (10011082), we get a palindrome (38022083).

The spelling of 28011001 in words is "twenty-eight million, eleven thousand, one".