91105821 has 6 divisors (see below), whose sum is σ = 131597310. Its totient is φ = 60737208.

The previous prime is 91105801. The next prime is 91105823. The reversal of 91105821 is 12850119.

It can be written as a sum of positive squares in only one way, i.e., 63920025 + 27185796 = 7995^2 + 5214^2 .

It is not a de Polignac number, because 91105821 - 2⁵ = 91105789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91105823) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5061426 + ... + 5061443.

It is an arithmetic number, because the mean of its divisors is an integer number (21932885).

Almost surely, 2^91105821 is an apocalyptic number.

It is an amenable number.

91105821 is a deficient number, since it is larger than the sum of its proper divisors (40491489).

91105821 is a wasteful number, since it uses less digits than its factorization.

91105821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10122875 (or 10122872 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 27.

The square root of 91105821 is about 9544.9369301216. The cubic root of 91105821 is about 449.9684274145.

The spelling of 91105821 in words is "ninety-one million, one hundred five thousand, eight hundred twenty-one".