28655581 has 2 divisors, whose sum is σ = 28655582. Its totient is φ = 28655580.

The previous prime is 28655503. The next prime is 28655593. The reversal of 28655581 is 18555682.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16475481 + 12180100 = 4059^2 + 3490^2 .

It is a cyclic number.

It is not a de Polignac number, because 28655581 - 2¹⁵ = 28622813 is a prime.

It is a super-2 number, since 2×28655581² = 1642284644895122, which contains 22 as substring.

It is equal to p_1779691 and since 28655581 and 1779691 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28655681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14327790 + 14327791.

It is an arithmetic number, because the mean of its divisors is an integer number (14327791).

Almost surely, 2^28655581 is an apocalyptic number.

It is an amenable number.

28655581 is a deficient number, since it is larger than the sum of its proper divisors (1).

28655581 is an equidigital number, since it uses as much as digits as its factorization.

28655581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 96000, while the sum is 40.

The square root of 28655581 is about 5353.0907894412. The cubic root of 28655581 is about 306.0105546931.

The spelling of 28655581 in words is "twenty-eight million, six hundred fifty-five thousand, five hundred eighty-one".