257197987 has 4 divisors (see below), whose sum is σ = 259223296. Its totient is φ = 255172680.

The previous prime is 257197949. The next prime is 257197991. The reversal of 257197987 is 789791752.

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 257197987 - 2⁷ = 257197859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (257197687) 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, 1012464 + ... + 1012717.

It is an arithmetic number, because the mean of its divisors is an integer number (64805824).

Almost surely, 2^257197987 is an apocalyptic number.

257197987 is a deficient number, since it is larger than the sum of its proper divisors (2025309).

257197987 is a wasteful number, since it uses less digits than its factorization.

257197987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2025308.

The product of its digits is 2222640, while the sum is 55.

The square root of 257197987 is about 16037.3933979310. The cubic root of 257197987 is about 635.9493411584.

The spelling of 257197987 in words is "two hundred fifty-seven million, one hundred ninety-seven thousand, nine hundred eighty-seven".