28491569 has 2 divisors, whose sum is σ = 28491570. Its totient is φ = 28491568.

The previous prime is 28491563. The next prime is 28491571. The reversal of 28491569 is 96519482.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21669025 + 6822544 = 4655^2 + 2612^2 .

It is a cyclic number.

It is not a de Polignac number, because 28491569 - 2⁴ = 28491553 is a prime.

It is a super-4 number, since 4×28491569⁴ (a number of 31 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Sophie Germain prime.

Together with 28491571, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (28491563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14245784 + 14245785.

It is an arithmetic number, because the mean of its divisors is an integer number (14245785).

Almost surely, 2^28491569 is an apocalyptic number.

It is an amenable number.

28491569 is a deficient number, since it is larger than the sum of its proper divisors (1).

28491569 is an equidigital number, since it uses as much as digits as its factorization.

28491569 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 155520, while the sum is 44.

The square root of 28491569 is about 5337.7494321109. The cubic root of 28491569 is about 305.4256138074.

The spelling of 28491569 in words is "twenty-eight million, four hundred ninety-one thousand, five hundred sixty-nine".