71819907991 has 16 divisors (see below), whose sum is σ = 78062019840. Its totient is φ = 65680796160.

The previous prime is 71819907989. The next prime is 71819908033. The reversal of 71819907991 is 19970991817.

It is a cyclic number.

It is not a de Polignac number, because 71819907991 - 2¹ = 71819907989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71819907791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3985221 + ... + 4003201.

It is an arithmetic number, because the mean of its divisors is an integer number (4878876240).

Almost surely, 2^71819907991 is an apocalyptic number.

71819907991 is a deficient number, since it is larger than the sum of its proper divisors (6242111849).

71819907991 is a wasteful number, since it uses less digits than its factorization.

71819907991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20826.

The product of its (nonzero) digits is 2571912, while the sum is 61.

The spelling of 71819907991 in words is "seventy-one billion, eight hundred nineteen million, nine hundred seven thousand, nine hundred ninety-one".