991235661143 has 24 divisors (see below), whose sum is σ = 1242454878000. Its totient is φ = 783840395520.

The previous prime is 991235661029. The next prime is 991235661161. The reversal of 991235661143 is 341166532199.

It is a de Polignac number, because none of the positive numbers 2^k-991235661143 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 991235661091 and 991235661100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991235660143) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 723983 + ... + 1583231.

It is an arithmetic number, because the mean of its divisors is an integer number (51768953250).

Almost surely, 2^991235661143 is an apocalyptic number.

991235661143 is a deficient number, since it is larger than the sum of its proper divisors (251219216857).

991235661143 is a wasteful number, since it uses less digits than its factorization.

991235661143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 861087 (or 861080 counting only the distinct ones).

The product of its digits is 1049760, while the sum is 50.

The spelling of 991235661143 in words is "nine hundred ninety-one billion, two hundred thirty-five million, six hundred sixty-one thousand, one hundred forty-three".