1287798257 has 2 divisors, whose sum is σ = 1287798258. Its totient is φ = 1287798256.

The previous prime is 1287798143. The next prime is 1287798269. The reversal of 1287798257 is 7528977821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1287302641 + 495616 = 35879^2 + 704^2 .

It is an emirp because it is prime and its reverse (7528977821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1287798257 - 2¹² = 1287794161 is a prime.

It is not a weakly prime, because it can be changed into another prime (1287798557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 643899128 + 643899129.

It is an arithmetic number, because the mean of its divisors is an integer number (643899129).

Almost surely, 2^1287798257 is an apocalyptic number.

It is an amenable number.

1287798257 is a deficient number, since it is larger than the sum of its proper divisors (1).

1287798257 is an equidigital number, since it uses as much as digits as its factorization.

1287798257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3951360, while the sum is 56.

The square root of 1287798257 is about 35885.9061053222. The cubic root of 1287798257 is about 1087.9675553622.

The spelling of 1287798257 in words is "one billion, two hundred eighty-seven million, seven hundred ninety-eight thousand, two hundred fifty-seven".