71991881809919 has 16 divisors (see below), whose sum is σ = 73970187793920. Its totient is φ = 70027827888480.

The previous prime is 71991881809907. The next prime is 71991881809957. The reversal of 71991881809919 is 91990818819917.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71991881809919 is a prime.

It is a super-2 number, since 2×71991881809919² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71991881809999) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11492222 + ... + 16614900.

It is an arithmetic number, because the mean of its divisors is an integer number (4623136737120).

Almost surely, 2^{71991881809919} is an apocalyptic number.

71991881809919 is a deficient number, since it is larger than the sum of its proper divisors (1978305984001).

71991881809919 is a wasteful number, since it uses less digits than its factorization.

71991881809919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5124070.

The product of its (nonzero) digits is 211631616, while the sum is 80.

The spelling of 71991881809919 in words is "seventy-one trillion, nine hundred ninety-one billion, eight hundred eighty-one million, eight hundred nine thousand, nine hundred nineteen".