257638139 has 4 divisors (see below), whose sum is σ = 281059800. Its totient is φ = 234216480.

The previous prime is 257638133. The next prime is 257638193. The reversal of 257638139 is 931836752.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-257638139 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 257638139.

It is not an unprimeable number, because it can be changed into a prime (257638133) 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, 11710814 + ... + 11710835.

It is an arithmetic number, because the mean of its divisors is an integer number (70264950).

Almost surely, 2^257638139 is an apocalyptic number.

257638139 is a deficient number, since it is larger than the sum of its proper divisors (23421661).

257638139 is a wasteful number, since it uses less digits than its factorization.

257638139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23421660.

The product of its digits is 272160, while the sum is 44.

The square root of 257638139 is about 16051.1102108234. The cubic root of 257638139 is about 636.3119086024.

The spelling of 257638139 in words is "two hundred fifty-seven million, six hundred thirty-eight thousand, one hundred thirty-nine".