257720403 has 4 divisors (see below), whose sum is σ = 343627208. Its totient is φ = 171813600.

The previous prime is 257720401. The next prime is 257720417. The reversal of 257720403 is 304027752.

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

It is not a de Polignac number, because 257720403 - 2¹ = 257720401 is a prime.

It is a super-2 number, since 2×257720403² = 132839612244964818, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (257720401) 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, 42953398 + ... + 42953403.

It is an arithmetic number, because the mean of its divisors is an integer number (85906802).

Almost surely, 2^257720403 is an apocalyptic number.

257720403 is a deficient number, since it is larger than the sum of its proper divisors (85906805).

257720403 is an equidigital number, since it uses as much as digits as its factorization.

257720403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85906804.

The product of its (nonzero) digits is 11760, while the sum is 30.

The square root of 257720403 is about 16053.6725704743. The cubic root of 257720403 is about 636.3796263100.

The spelling of 257720403 in words is "two hundred fifty-seven million, seven hundred twenty thousand, four hundred three".