28751581 has 2 divisors, whose sum is σ = 28751582. Its totient is φ = 28751580.

The previous prime is 28751551. The next prime is 28751603. The reversal of 28751581 is 18515782.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27994681 + 756900 = 5291^2 + 870^2 .

It is a cyclic number.

It is not a de Polignac number, because 28751581 - 2⁷ = 28751453 is a prime.

It is a super-2 number, since 2×28751581² = 1653306819999122, which contains 22 as substring.

It is equal to p_1785259 and since 28751581 and 1785259 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28751581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28751531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14375790 + 14375791.

It is an arithmetic number, because the mean of its divisors is an integer number (14375791).

Almost surely, 2^28751581 is an apocalyptic number.

It is an amenable number.

28751581 is a deficient number, since it is larger than the sum of its proper divisors (1).

28751581 is an equidigital number, since it uses as much as digits as its factorization.

28751581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22400, while the sum is 37.

The square root of 28751581 is about 5362.0500743652. The cubic root of 28751581 is about 306.3518991191.

The spelling of 28751581 in words is "twenty-eight million, seven hundred fifty-one thousand, five hundred eighty-one".