257240639 has 16 divisors (see below), whose sum is σ = 274834560. Its totient is φ = 240084000.

The previous prime is 257240611. The next prime is 257240647. The reversal of 257240639 is 936042752.

It is not a de Polignac number, because 257240639 - 2⁸ = 257240383 is a prime.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (257240609) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 450224 + ... + 450794.

It is an arithmetic number, because the mean of its divisors is an integer number (17177160).

Almost surely, 2^257240639 is an apocalyptic number.

257240639 is a deficient number, since it is larger than the sum of its proper divisors (17593921).

257240639 is a wasteful number, since it uses less digits than its factorization.

257240639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 902.

The product of its (nonzero) digits is 90720, while the sum is 38.

The square root of 257240639 is about 16038.7231100234. The cubic root of 257240639 is about 635.9844930821.

The spelling of 257240639 in words is "two hundred fifty-seven million, two hundred forty thousand, six hundred thirty-nine".