28715257 has 2 divisors, whose sum is σ = 28715258. Its totient is φ = 28715256.

The previous prime is 28715233. The next prime is 28715263. The reversal of 28715257 is 75251782.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 28100601 + 614656 = 5301^2 + 784^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28715257 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (28745257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14357628 + 14357629.

It is an arithmetic number, because the mean of its divisors is an integer number (14357629).

Almost surely, 2^28715257 is an apocalyptic number.

It is an amenable number.

28715257 is a deficient number, since it is larger than the sum of its proper divisors (1).

28715257 is an equidigital number, since it uses as much as digits as its factorization.

28715257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 39200, while the sum is 37.

The square root of 28715257 is about 5358.6618665484. The cubic root of 28715257 is about 306.2228324088. Note that the first 3 decimals are identical.

It can be divided in two parts, 2871 and 5257, that added together give a triangular number (8128 = T₁₂₇).

The spelling of 28715257 in words is "twenty-eight million, seven hundred fifteen thousand, two hundred fifty-seven".