71813309 has 4 divisors (see below), whose sum is σ = 74289660. Its totient is φ = 69336960.

The previous prime is 71813279. The next prime is 71813327. The reversal of 71813309 is 90331817.

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 19829209 + 51984100 = 4453^2 + 7210^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71813309 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71813009) 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, 1238132 + ... + 1238189.

It is an arithmetic number, because the mean of its divisors is an integer number (18572415).

Almost surely, 2^71813309 is an apocalyptic number.

It is an amenable number.

71813309 is a deficient number, since it is larger than the sum of its proper divisors (2476351).

71813309 is a wasteful number, since it uses less digits than its factorization.

71813309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2476350.

The product of its (nonzero) digits is 4536, while the sum is 32.

The square root of 71813309 is about 8474.2733611797. The cubic root of 71813309 is about 415.6568858572.

The spelling of 71813309 in words is "seventy-one million, eight hundred thirteen thousand, three hundred nine".