1991193697 has 8 divisors (see below), whose sum is σ = 2199989376. Its totient is φ = 1792583232.

The previous prime is 1991193691. The next prime is 1991193713. The reversal of 1991193697 is 7963911991.

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 1991193697 - 2²³ = 1982805089 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1991193691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2545893 + ... + 2546674.

It is an arithmetic number, because the mean of its divisors is an integer number (274998672).

Almost surely, 2^1991193697 is an apocalyptic number.

1991193697 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

1991193697 is a deficient number, since it is larger than the sum of its proper divisors (208795679).

1991193697 is a wasteful number, since it uses less digits than its factorization.

1991193697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5092607.

The product of its digits is 826686, while the sum is 55.

The square root of 1991193697 is about 44622.7934692574. The cubic root of 1991193697 is about 1258.0691213685.

The spelling of 1991193697 in words is "one billion, nine hundred ninety-one million, one hundred ninety-three thousand, six hundred ninety-seven".