91856523487 has 4 divisors (see below), whose sum is σ = 97259848416. Its totient is φ = 86453198560.

The previous prime is 91856523463. The next prime is 91856523497. The reversal of 91856523487 is 78432565819.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78432565819 = 3067 ⋅25573057.

It is a cyclic number.

It is not a de Polignac number, because 91856523487 - 2³¹ = 89709039839 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91856523457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2701662439 + ... + 2701662472.

It is an arithmetic number, because the mean of its divisors is an integer number (24314962104).

Almost surely, 2^91856523487 is an apocalyptic number.

91856523487 is a deficient number, since it is larger than the sum of its proper divisors (5403324929).

91856523487 is a wasteful number, since it uses less digits than its factorization.

91856523487 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5403324928.

The product of its digits is 14515200, while the sum is 58.

The spelling of 91856523487 in words is "ninety-one billion, eight hundred fifty-six million, five hundred twenty-three thousand, four hundred eighty-seven".