91111001820 has 48 divisors (see below), whose sum is σ = 255247469568. Its totient is φ = 24283251520.

The previous prime is 91111001819. The next prime is 91111001843. The reversal of 91111001820 is 2810011119.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 293544 + ... + 518063.

It is an arithmetic number, because the mean of its divisors is an integer number (5317655616).

Almost surely, 2^91111001820 is an apocalyptic number.

It is an amenable number.

91111001820 is an abundant number, since it is smaller than the sum of its proper divisors (164136467748).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

91111001820 is a wasteful number, since it uses less digits than its factorization.

91111001820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 813490 (or 813488 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 24.

Adding to 91111001820 its reverse (2810011119), we get a palindrome (93921012939).

The spelling of 91111001820 in words is "ninety-one billion, one hundred eleven million, one thousand, eight hundred twenty".