197191681 has 4 divisors (see below), whose sum is σ = 198192852. Its totient is φ = 196190512.

The previous prime is 197191613. The next prime is 197191697. The reversal of 197191681 is 186191791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 186191791 = 97 ⋅1919503.

It can be written as a sum of positive squares in 2 ways, for example, as 99181681 + 98010000 = 9959^2 + 9900^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-197191681 is a prime.

It is a super-2 number, since 2×197191681² = 77769118111211522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (197191601) 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, 500290 + ... + 500683.

It is an arithmetic number, because the mean of its divisors is an integer number (49548213).

Almost surely, 2^197191681 is an apocalyptic number.

It is an amenable number.

197191681 is a deficient number, since it is larger than the sum of its proper divisors (1001171).

197191681 is a wasteful number, since it uses less digits than its factorization.

197191681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1001170.

The product of its digits is 27216, while the sum is 43.

The square root of 197191681 is about 14042.4955403233. The cubic root of 197191681 is about 582.0534437210.

The spelling of 197191681 in words is "one hundred ninety-seven million, one hundred ninety-one thousand, six hundred eighty-one".