91999720869 has 8 divisors (see below), whose sum is σ = 140190050880. Its totient is φ = 52571269056.

The previous prime is 91999720867. The next prime is 91999720873. The reversal of 91999720869 is 96802799919.

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

It is not a de Polignac number, because 91999720869 - 2¹ = 91999720867 is a prime.

It is a super-2 number, since 2×91999720869² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91999720867) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2190469524 + ... + 2190469565.

It is an arithmetic number, because the mean of its divisors is an integer number (17523756360).

Almost surely, 2^91999720869 is an apocalyptic number.

It is an amenable number.

91999720869 is a deficient number, since it is larger than the sum of its proper divisors (48190330011).

91999720869 is a wasteful number, since it uses less digits than its factorization.

91999720869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4380939099.

The product of its (nonzero) digits is 39680928, while the sum is 69.

The spelling of 91999720869 in words is "ninety-one billion, nine hundred ninety-nine million, seven hundred twenty thousand, eight hundred sixty-nine".