28811641 has 4 divisors (see below), whose sum is σ = 29590372. Its totient is φ = 28032912.

The previous prime is 28811623. The next prime is 28811659. The reversal of 28811641 is 14611882.

28811641 = 3795² + 3796².

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (28811623) and next prime (28811659).

It can be written as a sum of positive squares in 2 ways, for example, as 14402025 + 14409616 = 3795^2 + 3796^2 .

It is a cyclic number.

It is not a de Polignac number, because 28811641 - 2⁵ = 28811609 is a prime.

It is a super-2 number, since 2×28811641² = 1660221314225762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28811621) 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, 389310 + ... + 389383.

It is an arithmetic number, because the mean of its divisors is an integer number (7397593).

Almost surely, 2^28811641 is an apocalyptic number.

28811641 is the 3796-th centered square number.

It is an amenable number.

28811641 is a deficient number, since it is larger than the sum of its proper divisors (778731).

28811641 is an equidigital number, since it uses as much as digits as its factorization.

28811641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 778730.

The product of its digits is 3072, while the sum is 31.

The square root of 28811641 is about 5367.6476225624. The cubic root of 28811641 is about 306.5650665059.

The spelling of 28811641 in words is "twenty-eight million, eight hundred eleven thousand, six hundred forty-one".