197085807991 has 4 divisors (see below), whose sum is σ = 208679090832. Its totient is φ = 185492525152.

The previous prime is 197085807943. The next prime is 197085808001. The reversal of 197085807991 is 199708580791.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199708580791 = 317 ⋅629995523.

It is a cyclic number.

It is not a de Polignac number, because 197085807991 - 2¹⁵ = 197085775223 is a prime.

It is a super-2 number, since 2×197085807991² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (197085807911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5796641395 + ... + 5796641428.

It is an arithmetic number, because the mean of its divisors is an integer number (52169772708).

Almost surely, 2^197085807991 is an apocalyptic number.

197085807991 is a deficient number, since it is larger than the sum of its proper divisors (11593282841).

197085807991 is a wasteful number, since it uses less digits than its factorization.

197085807991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11593282840.

The product of its (nonzero) digits is 11430720, while the sum is 64.

The spelling of 197085807991 in words is "one hundred ninety-seven billion, eighty-five million, eight hundred seven thousand, nine hundred ninety-one".