28717561 has 2 divisors, whose sum is σ = 28717562. Its totient is φ = 28717560.

The previous prime is 28717553. The next prime is 28717567. The reversal of 28717561 is 16571782.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27625536 + 1092025 = 5256^2 + 1045^2 .

It is a cyclic number.

It is not a de Polignac number, because 28717561 - 2³ = 28717553 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28717561.

It is not a weakly prime, because it can be changed into another prime (28717567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14358780 + 14358781.

It is an arithmetic number, because the mean of its divisors is an integer number (14358781).

Almost surely, 2^28717561 is an apocalyptic number.

It is an amenable number.

28717561 is a deficient number, since it is larger than the sum of its proper divisors (1).

28717561 is an equidigital number, since it uses as much as digits as its factorization.

28717561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23520, while the sum is 37.

The square root of 28717561 is about 5358.8768412793. The cubic root of 28717561 is about 306.2310222309.

The spelling of 28717561 in words is "twenty-eight million, seven hundred seventeen thousand, five hundred sixty-one".