71661565 has 8 divisors (see below), whose sum is σ = 87616728. Its totient is φ = 56247360.

The previous prime is 71661533. The next prime is 71661571. The reversal of 71661565 is 56516617.

It can be written as a sum of positive squares in 4 ways, for example, as 14417209 + 57244356 = 3797^2 + 7566^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 71661565 - 2⁵ = 71661533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 134946 + ... + 135475.

It is an arithmetic number, because the mean of its divisors is an integer number (10952091).

Almost surely, 2^71661565 is an apocalyptic number.

It is an amenable number.

71661565 is a deficient number, since it is larger than the sum of its proper divisors (15955163).

71661565 is a wasteful number, since it uses less digits than its factorization.

71661565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270479.

The product of its digits is 37800, while the sum is 37.

The square root of 71661565 is about 8465.3154105444. The cubic root of 71661565 is about 415.3639136257.

The spelling of 71661565 in words is "seventy-one million, six hundred sixty-one thousand, five hundred sixty-five".