91091020091 has 4 divisors (see below), whose sum is σ = 91091722800. Its totient is φ = 91090317384.

The previous prime is 91091020087. The next prime is 91091020103. The reversal of 91091020091 is 19002019019.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 91091020091 - 2² = 91091020087 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91091220091) 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, 94151 + ... + 437088.

It is an arithmetic number, because the mean of its divisors is an integer number (22772930700).

Almost surely, 2^91091020091 is an apocalyptic number.

91091020091 is a deficient number, since it is larger than the sum of its proper divisors (702709).

91091020091 is a wasteful number, since it uses less digits than its factorization.

91091020091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 702708.

The product of its (nonzero) digits is 1458, while the sum is 32.

The spelling of 91091020091 in words is "ninety-one billion, ninety-one million, twenty thousand, ninety-one".