1991548847 has 4 divisors (see below), whose sum is σ = 1993057776. Its totient is φ = 1990039920.

The previous prime is 1991548837. The next prime is 1991548873. The reversal of 1991548847 is 7488451991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7488451991 = 53 ⋅141291547.

It is a cyclic number.

It is not a de Polignac number, because 1991548847 - 2¹⁶ = 1991483311 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1991548792 and 1991548801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991548837) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 752483 + ... + 755124.

It is an arithmetic number, because the mean of its divisors is an integer number (498264444).

Almost surely, 2^1991548847 is an apocalyptic number.

1991548847 is a deficient number, since it is larger than the sum of its proper divisors (1508929).

1991548847 is a wasteful number, since it uses less digits than its factorization.

1991548847 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1508928.

The product of its digits is 2903040, while the sum is 56.

The square root of 1991548847 is about 44626.7727603061. The cubic root of 1991548847 is about 1258.1439134707.

The spelling of 1991548847 in words is "one billion, nine hundred ninety-one million, five hundred forty-eight thousand, eight hundred forty-seven".