28605581 has 2 divisors, whose sum is σ = 28605582. Its totient is φ = 28605580.

The previous prime is 28605569. The next prime is 28605589. The reversal of 28605581 is 18550682.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25664356 + 2941225 = 5066^2 + 1715^2 .

It is a cyclic number.

It is not a de Polignac number, because 28605581 - 2⁶ = 28605517 is a prime.

It is a super-2 number, since 2×28605581² = 1636558528695122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28605589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14302790 + 14302791.

It is an arithmetic number, because the mean of its divisors is an integer number (14302791).

Almost surely, 2^28605581 is an apocalyptic number.

It is an amenable number.

28605581 is a deficient number, since it is larger than the sum of its proper divisors (1).

28605581 is an equidigital number, since it uses as much as digits as its factorization.

28605581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19200, while the sum is 35.

The square root of 28605581 is about 5348.4185513103. The cubic root of 28605581 is about 305.8324691343.

The spelling of 28605581 in words is "twenty-eight million, six hundred five thousand, five hundred eighty-one".