28236581 has 2 divisors, whose sum is σ = 28236582. Its totient is φ = 28236580.

The previous prime is 28236539. The next prime is 28236583. The reversal of 28236581 is 18563282.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20205025 + 8031556 = 4495^2 + 2834^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28236581 is a prime.

It is a super-2 number, since 2×28236581² = 1594609013139122, which contains 22 as substring.

Together with 28236583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28236583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14118290 + 14118291.

It is an arithmetic number, because the mean of its divisors is an integer number (14118291).

Almost surely, 2^28236581 is an apocalyptic number.

It is an amenable number.

28236581 is a deficient number, since it is larger than the sum of its proper divisors (1).

28236581 is an equidigital number, since it uses as much as digits as its factorization.

28236581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23040, while the sum is 35.

The square root of 28236581 is about 5313.8104030912. The cubic root of 28236581 is about 304.5117369153.

It can be divided in two parts, 282 and 36581, that added together give a palindrome (36863).

The spelling of 28236581 in words is "twenty-eight million, two hundred thirty-six thousand, five hundred eighty-one".