91408866221 has 4 divisors (see below), whose sum is σ = 96219859200. Its totient is φ = 86597873244.

The previous prime is 91408866191. The next prime is 91408866223. The reversal of 91408866221 is 12266880419.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 91408866221 - 2²⁶ = 91341757357 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 (91408866223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2405496461 + ... + 2405496498.

It is an arithmetic number, because the mean of its divisors is an integer number (24054964800).

Almost surely, 2^91408866221 is an apocalyptic number.

It is an amenable number.

91408866221 is a deficient number, since it is larger than the sum of its proper divisors (4810992979).

91408866221 is a wasteful number, since it uses less digits than its factorization.

91408866221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4810992978.

The product of its (nonzero) digits is 331776, while the sum is 47.

The spelling of 91408866221 in words is "ninety-one billion, four hundred eight million, eight hundred sixty-six thousand, two hundred twenty-one".