991090100100 has 72 divisors (see below), whose sum is σ = 2894353687008. Its totient is φ = 261820678400.

The previous prime is 991090100087. The next prime is 991090100113. The reversal of 991090100100 is 1001090199.

It is an interprime number because it is at equal distance from previous prime (991090100087) and next prime (991090100113).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15405441 + ... + 15469640.

It is an arithmetic number, because the mean of its divisors is an integer number (40199356764).

Almost surely, 2^991090100100 is an apocalyptic number.

It is an amenable number.

991090100100 is an abundant number, since it is smaller than the sum of its proper divisors (1903263586908).

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

991090100100 is a wasteful number, since it uses less digits than its factorization.

991090100100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30875205 (or 30875198 counting only the distinct ones).

The product of its (nonzero) digits is 729, while the sum is 30.

Adding to 991090100100 its reverse (1001090199), we get a palindrome (992091190299).

The spelling of 991090100100 in words is "nine hundred ninety-one billion, ninety million, one hundred thousand, one hundred".