991805172749 has 8 divisors (see below), whose sum is σ = 993850972800. Its totient is φ = 989761285296.

The previous prime is 991805172737. The next prime is 991805172763. The reversal of 991805172749 is 947271508199.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 991805172749 - 2¹⁶ = 991805107213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 991805172691 and 991805172700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991805072749) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 562379 + ... + 1516535.

It is an arithmetic number, because the mean of its divisors is an integer number (124231371600).

Almost surely, 2^991805172749 is an apocalyptic number.

It is an amenable number.

991805172749 is a deficient number, since it is larger than the sum of its proper divisors (2045800051).

991805172749 is a wasteful number, since it uses less digits than its factorization.

991805172749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 956299.

The product of its (nonzero) digits is 11430720, while the sum is 62.

The spelling of 991805172749 in words is "nine hundred ninety-one billion, eight hundred five million, one hundred seventy-two thousand, seven hundred forty-nine".