257720347 has 2 divisors, whose sum is σ = 257720348. Its totient is φ = 257720346.

The previous prime is 257720341. The next prime is 257720381. The reversal of 257720347 is 743027752.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 257720347 - 2²³ = 249331739 is a prime.

It is not a weakly prime, because it can be changed into another prime (257720341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128860173 + 128860174.

It is an arithmetic number, because the mean of its divisors is an integer number (128860174).

Almost surely, 2^257720347 is an apocalyptic number.

257720347 is a deficient number, since it is larger than the sum of its proper divisors (1).

257720347 is an equidigital number, since it uses as much as digits as its factorization.

257720347 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 82320, while the sum is 37.

The square root of 257720347 is about 16053.6708263250. The cubic root of 257720347 is about 636.3795802171.

The spelling of 257720347 in words is "two hundred fifty-seven million, seven hundred twenty thousand, three hundred forty-seven".