91821887 has 4 divisors (see below), whose sum is σ = 91953576. Its totient is φ = 91690200.

The previous prime is 91821869. The next prime is 91821893. The reversal of 91821887 is 78812819.

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 91821887 - 2⁶ = 91821823 is a prime.

It is a super-3 number, since 3×91821887³ (a number of 25 digits) contains 333 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 (91821857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64793 + ... + 66194.

It is an arithmetic number, because the mean of its divisors is an integer number (22988394).

Almost surely, 2^91821887 is an apocalyptic number.

91821887 is a deficient number, since it is larger than the sum of its proper divisors (131689).

91821887 is a wasteful number, since it uses less digits than its factorization.

91821887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131688.

The product of its digits is 64512, while the sum is 44.

The square root of 91821887 is about 9582.3737664527. The cubic root of 91821887 is about 451.1442271713.

The spelling of 91821887 in words is "ninety-one million, eight hundred twenty-one thousand, eight hundred eighty-seven".