71031809 has 4 divisors (see below), whose sum is σ = 71059716. Its totient is φ = 71003904.

The previous prime is 71031799. The next prime is 71031827. The reversal of 71031809 is 90813017.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90813017 = 4201 ⋅21617.

It can be written as a sum of positive squares in 2 ways, for example, as 28090000 + 42941809 = 5300^2 + 6553^2 .

It is a cyclic number.

It is not a de Polignac number, because 71031809 - 2¹² = 71027713 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (71030809) 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, 9704 + ... + 15369.

It is an arithmetic number, because the mean of its divisors is an integer number (17764929).

Almost surely, 2^71031809 is an apocalyptic number.

It is an amenable number.

71031809 is a deficient number, since it is larger than the sum of its proper divisors (27907).

71031809 is a wasteful number, since it uses less digits than its factorization.

71031809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27906.

The product of its (nonzero) digits is 1512, while the sum is 29.

The square root of 71031809 is about 8428.0370787034. The cubic root of 71031809 is about 414.1436038656.

The spelling of 71031809 in words is "seventy-one million, thirty-one thousand, eight hundred nine".