28557509 has 2 divisors, whose sum is σ = 28557510. Its totient is φ = 28557508.

The previous prime is 28557499. The next prime is 28557511. The reversal of 28557509 is 90575582.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27269284 + 1288225 = 5222^2 + 1135^2 .

It is a cyclic number.

It is not a de Polignac number, because 28557509 - 2⁴ = 28557493 is a prime.

Together with 28557511, 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 (28557539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14278754 + 14278755.

It is an arithmetic number, because the mean of its divisors is an integer number (14278755).

Almost surely, 2^28557509 is an apocalyptic number.

It is an amenable number.

28557509 is a deficient number, since it is larger than the sum of its proper divisors (1).

28557509 is an equidigital number, since it uses as much as digits as its factorization.

28557509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 126000, while the sum is 41.

The square root of 28557509 is about 5343.9226229428. The cubic root of 28557509 is about 305.6610547779.

The spelling of 28557509 in words is "twenty-eight million, five hundred fifty-seven thousand, five hundred nine".