91999999999999 has 8 divisors (see below), whose sum is σ = 113230769230880. Its totient is φ = 72791208791136.

The previous prime is 91999999999997. The next prime is 92000000000033. The reversal of 91999999999999 is 99999999999919.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 91999999999999 - 2¹ = 91999999999997 is a prime.

It is a super-9 number, since 9×91999999999999⁹ (a number of 127 digits) contains 999999999 as substring.

91999999999999 is a modest number, since divided by 9999999 gives 9199999 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91999999999997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 505494505404 + ... + 505494505585.

It is an arithmetic number, because the mean of its divisors is an integer number (14153846153860).

Almost surely, 2^{91999999999999} is an apocalyptic number.

91999999999999 is a deficient number, since it is larger than the sum of its proper divisors (21230769230881).

91999999999999 is a wasteful number, since it uses less digits than its factorization.

91999999999999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1010989011009.

The product of its digits is 2541865828329, while the sum is 118.

It can be divided in two parts, 91 and 999999999999, that multiplied together give a palindrome (90999999999909).

The spelling of 91999999999999 in words is "ninety-one trillion, nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred ninety-nine".