257666705 has 16 divisors (see below), whose sum is σ = 336240720. Its totient is φ = 188762112.

The previous prime is 257666701. The next prime is 257666729. The reversal of 257666705 is 507666752.

It is a Cunningham number, because it is equal to 16052²+1.

It can be written as a sum of positive squares in 8 ways, for example, as 6031936 + 251634769 = 2456^2 + 15863^2 .

It is a cyclic number.

It is not a de Polignac number, because 257666705 - 2² = 257666701 is a prime.

It is not an unprimeable number, because it can be changed into a prime (257666701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37820 + ... + 44109.

It is an arithmetic number, because the mean of its divisors is an integer number (21015045).

Almost surely, 2^257666705 is an apocalyptic number.

It is an amenable number.

257666705 is a deficient number, since it is larger than the sum of its proper divisors (78574015).

257666705 is a wasteful number, since it uses less digits than its factorization.

257666705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81988.

The product of its (nonzero) digits is 529200, while the sum is 44.

The square root of 257666705 is about 16052.0000311488. Note that the first 4 decimals coincide. The cubic root of 257666705 is about 636.3354250666.

The spelling of 257666705 in words is "two hundred fifty-seven million, six hundred sixty-six thousand, seven hundred five".