9891123291840 has 224 divisors, whose sum is σ = 37128256634880. Its totient is φ = 2182868545536.

The previous prime is 9891123291823. The next prime is 9891123291853. The reversal of 9891123291840 is 481923211989.

It is a tau number, because it is divible by the number of its divisors (224).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 25182592 + ... + 25572351.

Almost surely, 2^{9891123291840} is an apocalyptic number.

It is an amenable number.

9891123291840 is an abundant number, since it is smaller than the sum of its proper divisors (27237133343040).

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

9891123291840 is a wasteful number, since it uses less digits than its factorization.

9891123291840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50754999 (or 50754989 counting only the distinct ones).

The product of its (nonzero) digits is 2239488, while the sum is 57.

The spelling of 9891123291840 in words is "nine trillion, eight hundred ninety-one billion, one hundred twenty-three million, two hundred ninety-one thousand, eight hundred forty".