71810221561 has 16 divisors (see below), whose sum is σ = 77958074880. Its totient is φ = 65752341120.

The previous prime is 71810221559. The next prime is 71810221583. The reversal of 71810221561 is 16512201817.

It is a cyclic number.

It is not a de Polignac number, because 71810221561 - 2¹ = 71810221559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71810221501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2139096 + ... + 2172406.

It is an arithmetic number, because the mean of its divisors is an integer number (4872379680).

Almost surely, 2^71810221561 is an apocalyptic number.

It is an amenable number.

71810221561 is a deficient number, since it is larger than the sum of its proper divisors (6147853319).

71810221561 is a wasteful number, since it uses less digits than its factorization.

71810221561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34656.

The product of its (nonzero) digits is 6720, while the sum is 34.

The spelling of 71810221561 in words is "seventy-one billion, eight hundred ten million, two hundred twenty-one thousand, five hundred sixty-one".