71011561 has 4 divisors (see below), whose sum is σ = 71194500. Its totient is φ = 70828624.

The previous prime is 71011543. The next prime is 71011579. The reversal of 71011561 is 16511017.

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

It is an interprime number because it is at equal distance from previous prime (71011543) and next prime (71011579).

It can be written as a sum of positive squares in 2 ways, for example, as 31573161 + 39438400 = 5619^2 + 6280^2 .

It is a cyclic number.

It is not a de Polignac number, because 71011561 - 2⁵ = 71011529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71011861) 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, 90886 + ... + 91663.

It is an arithmetic number, because the mean of its divisors is an integer number (17798625).

Almost surely, 2^71011561 is an apocalyptic number.

It is an amenable number.

71011561 is a deficient number, since it is larger than the sum of its proper divisors (182939).

71011561 is a wasteful number, since it uses less digits than its factorization.

71011561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182938.

The product of its (nonzero) digits is 210, while the sum is 22.

The square root of 71011561 is about 8426.8357643899. The cubic root of 71011561 is about 414.1042488371.

Adding to 71011561 its reverse (16511017), we get a palindrome (87522578).

The spelling of 71011561 in words is "seventy-one million, eleven thousand, five hundred sixty-one".