71057209 has 4 divisors (see below), whose sum is σ = 71709220. Its totient is φ = 70405200.

The previous prime is 71057201. The next prime is 71057219. The reversal of 71057209 is 90275017.

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 43599609 + 27457600 = 6603^2 + 5240^2 .

It is a cyclic number.

It is not a de Polignac number, because 71057209 - 2³ = 71057201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71057201) 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, 325842 + ... + 326059.

It is an arithmetic number, because the mean of its divisors is an integer number (17927305).

Almost surely, 2^71057209 is an apocalyptic number.

It is an amenable number.

71057209 is a deficient number, since it is larger than the sum of its proper divisors (652011).

71057209 is a wasteful number, since it uses less digits than its factorization.

71057209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 652010.

The product of its (nonzero) digits is 4410, while the sum is 31.

The square root of 71057209 is about 8429.5438192111. The cubic root of 71057209 is about 414.1929620057.

The spelling of 71057209 in words is "seventy-one million, fifty-seven thousand, two hundred nine".