257215505 has 4 divisors (see below), whose sum is σ = 308658612. Its totient is φ = 205772400.

The previous prime is 257215501. The next prime is 257215507. The reversal of 257215505 is 505512752.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 129254161 + 127961344 = 11369^2 + 11312^2 .

It is not a de Polignac number, because 257215505 - 2² = 257215501 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (257215501) 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 in 3 ways as a sum of consecutive naturals, for example, 25721546 + ... + 25721555.

It is an arithmetic number, because the mean of its divisors is an integer number (77164653).

Almost surely, 2^257215505 is an apocalyptic number.

It is an amenable number.

257215505 is a deficient number, since it is larger than the sum of its proper divisors (51443107).

257215505 is an equidigital number, since it uses as much as digits as its factorization.

257215505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51443106.

The product of its (nonzero) digits is 17500, while the sum is 32.

The square root of 257215505 is about 16037.9395497053. The cubic root of 257215505 is about 635.9637792025.

The spelling of 257215505 in words is "two hundred fifty-seven million, two hundred fifteen thousand, five hundred five".