71687257 has 4 divisors (see below), whose sum is σ = 71775396. Its totient is φ = 71599120.

The previous prime is 71687233. The next prime is 71687269. The reversal of 71687257 is 75278617.

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

It can be written as a sum of positive squares in 2 ways, for example, as 17943696 + 53743561 = 4236^2 + 7331^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71687257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71687857) 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, 42838 + ... + 44479.

It is an arithmetic number, because the mean of its divisors is an integer number (17943849).

Almost surely, 2^71687257 is an apocalyptic number.

It is an amenable number.

71687257 is a deficient number, since it is larger than the sum of its proper divisors (88139).

71687257 is an equidigital number, since it uses as much as digits as its factorization.

71687257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88138.

The product of its digits is 164640, while the sum is 43.

The square root of 71687257 is about 8466.8327608380. The cubic root of 71687257 is about 415.4135462501.

The spelling of 71687257 in words is "seventy-one million, six hundred eighty-seven thousand, two hundred fifty-seven".