91112815021 has 4 divisors (see below), whose sum is σ = 93335078844. Its totient is φ = 88890551200.

The previous prime is 91112815009. The next prime is 91112815039. The reversal of 91112815021 is 12051821119.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 30158142921 + 60954672100 = 173661^2 + 246890^2 .

It is a cyclic number.

It is not a de Polignac number, because 91112815021 - 2³¹ = 88965331373 is a prime.

It is a super-2 number, since 2×91112815021² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91112815621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1111131850 + ... + 1111131931.

It is an arithmetic number, because the mean of its divisors is an integer number (23333769711).

Almost surely, 2^91112815021 is an apocalyptic number.

It is an amenable number.

91112815021 is a deficient number, since it is larger than the sum of its proper divisors (2222263823).

91112815021 is a wasteful number, since it uses less digits than its factorization.

91112815021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2222263822.

The product of its (nonzero) digits is 1440, while the sum is 31.

The spelling of 91112815021 in words is "ninety-one billion, one hundred twelve million, eight hundred fifteen thousand, twenty-one".