28915561 has 2 divisors, whose sum is σ = 28915562. Its totient is φ = 28915560.

The previous prime is 28915559. The next prime is 28915571. The reversal of 28915561 is 16551982.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27825625 + 1089936 = 5275^2 + 1044^2 .

It is a cyclic number.

It is not a de Polignac number, because 28915561 - 2¹ = 28915559 is a prime.

It is a super-2 number, since 2×28915561² = 1672219335889442, which contains 22 as substring.

Together with 28915559, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 28915561.

It is not a weakly prime, because it can be changed into another prime (28915571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14457780 + 14457781.

It is an arithmetic number, because the mean of its divisors is an integer number (14457781).

Almost surely, 2^28915561 is an apocalyptic number.

It is an amenable number.

28915561 is a deficient number, since it is larger than the sum of its proper divisors (1).

28915561 is an equidigital number, since it uses as much as digits as its factorization.

28915561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21600, while the sum is 37.

The square root of 28915561 is about 5377.3191275951. The cubic root of 28915561 is about 306.9332049188.

The spelling of 28915561 in words is "twenty-eight million, nine hundred fifteen thousand, five hundred sixty-one".