91921428087 has 4 divisors (see below), whose sum is σ = 122561904120. Its totient is φ = 61280952056.

The previous prime is 91921428083. The next prime is 91921428101. The reversal of 91921428087 is 78082412919.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 91921428087 - 2² = 91921428083 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91921428083) 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, 15320238012 + ... + 15320238017.

It is an arithmetic number, because the mean of its divisors is an integer number (30640476030).

Almost surely, 2^91921428087 is an apocalyptic number.

91921428087 is a deficient number, since it is larger than the sum of its proper divisors (30640476033).

91921428087 is a wasteful number, since it uses less digits than its factorization.

91921428087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30640476032.

The product of its (nonzero) digits is 580608, while the sum is 51.

The spelling of 91921428087 in words is "ninety-one billion, nine hundred twenty-one million, four hundred twenty-eight thousand, eighty-seven".