71521805 has 16 divisors (see below), whose sum is σ = 93809664. Its totient is φ = 52112640.

The previous prime is 71521799. The next prime is 71521843. The reversal of 71521805 is 50812517.

It is not a de Polignac number, because 71521805 - 2¹⁰ = 71520781 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10937 + ... + 16206.

It is an arithmetic number, because the mean of its divisors is an integer number (5863104).

Almost surely, 2^71521805 is an apocalyptic number.

It is an amenable number.

71521805 is a deficient number, since it is larger than the sum of its proper divisors (22287859).

71521805 is a wasteful number, since it uses less digits than its factorization.

71521805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27196.

The product of its (nonzero) digits is 2800, while the sum is 29.

The square root of 71521805 is about 8457.0565210361. The cubic root of 71521805 is about 415.0937128088.

The spelling of 71521805 in words is "seventy-one million, five hundred twenty-one thousand, eight hundred five".