91811901901 has 4 divisors (see below), whose sum is σ = 91812666304. Its totient is φ = 91811137500.

The previous prime is 91811901899. The next prime is 91811901913. The reversal of 91811901901 is 10910911819.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 10910911819 = 97 ⋅112483627.

It is a cyclic number.

It is not a de Polignac number, because 91811901901 - 2¹ = 91811901899 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 (91811901001) 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, 158325 + ... + 456826.

It is an arithmetic number, because the mean of its divisors is an integer number (22953166576).

Almost surely, 2^91811901901 is an apocalyptic number.

It is an amenable number.

91811901901 is a deficient number, since it is larger than the sum of its proper divisors (764403).

91811901901 is a wasteful number, since it uses less digits than its factorization.

91811901901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 764402.

The product of its (nonzero) digits is 5832, while the sum is 40.

The spelling of 91811901901 in words is "ninety-one billion, eight hundred eleven million, nine hundred one thousand, nine hundred one".