71116561 has 4 divisors (see below), whose sum is σ = 71133732. Its totient is φ = 71099392.

The previous prime is 71116541. The next prime is 71116579. The reversal of 71116561 is 16561117.

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 31979025 + 39137536 = 5655^2 + 6256^2 .

It is a cyclic number.

It is not a de Polignac number, because 71116561 - 2¹⁹ = 70592273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71116501) 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, 1881 + ... + 12073.

It is an arithmetic number, because the mean of its divisors is an integer number (17783433).

Almost surely, 2^71116561 is an apocalyptic number.

It is an amenable number.

71116561 is a deficient number, since it is larger than the sum of its proper divisors (17171).

71116561 is a wasteful number, since it uses less digits than its factorization.

71116561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17170.

The product of its digits is 1260, while the sum is 28.

The square root of 71116561 is about 8433.0635595850. The cubic root of 71116561 is about 414.3082509851.

Adding to 71116561 its reverse (16561117), we get a palindrome (87677678).

The spelling of 71116561 in words is "seventy-one million, one hundred sixteen thousand, five hundred sixty-one".