257191491 has 4 divisors (see below), whose sum is σ = 342921992. Its totient is φ = 171460992.

The previous prime is 257191423. The next prime is 257191499. The reversal of 257191491 is 194191752.

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

It is not a de Polignac number, because 257191491 - 2⁹ = 257190979 is a prime.

It is a super-2 number, since 2×257191491² = 132294926085606162, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (257191499) 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, 42865246 + ... + 42865251.

It is an arithmetic number, because the mean of its divisors is an integer number (85730498).

Almost surely, 2^257191491 is an apocalyptic number.

257191491 is a deficient number, since it is larger than the sum of its proper divisors (85730501).

257191491 is an equidigital number, since it uses as much as digits as its factorization.

257191491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85730500.

The product of its digits is 22680, while the sum is 39.

The square root of 257191491 is about 16037.1908699747. The cubic root of 257191491 is about 635.9439870966.

The spelling of 257191491 in words is "two hundred fifty-seven million, one hundred ninety-one thousand, four hundred ninety-one".