257205643647 has 4 divisors (see below), whose sum is σ = 342940858200. Its totient is φ = 171470429096.

The previous prime is 257205643579. The next prime is 257205643649. The reversal of 257205643647 is 746346502752.

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

It is a cyclic number.

It is not a de Polignac number, because 257205643647 - 2¹⁶ = 257205578111 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 257205643647.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (257205643649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42867607272 + ... + 42867607277.

It is an arithmetic number, because the mean of its divisors is an integer number (85735214550).

Almost surely, 2^257205643647 is an apocalyptic number.

257205643647 is a deficient number, since it is larger than the sum of its proper divisors (85735214553).

257205643647 is an equidigital number, since it uses as much as digits as its factorization.

257205643647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85735214552.

The product of its (nonzero) digits is 8467200, while the sum is 51.

The spelling of 257205643647 in words is "two hundred fifty-seven billion, two hundred five million, six hundred forty-three thousand, six hundred forty-seven".