197728391 has 4 divisors (see below), whose sum is σ = 225975312. Its totient is φ = 169481472.

The previous prime is 197728381. The next prime is 197728423. The reversal of 197728391 is 193827791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 193827791 = 199 ⋅974009.

It is a cyclic number.

It is not a de Polignac number, because 197728391 - 2¹⁰ = 197727367 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (197728381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14123450 + ... + 14123463.

It is an arithmetic number, because the mean of its divisors is an integer number (56493828).

Almost surely, 2^197728391 is an apocalyptic number.

197728391 is a deficient number, since it is larger than the sum of its proper divisors (28246921).

197728391 is an equidigital number, since it uses as much as digits as its factorization.

197728391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28246920.

The product of its digits is 190512, while the sum is 47.

The square root of 197728391 is about 14061.5927618460. The cubic root of 197728391 is about 582.5810368202.

The spelling of 197728391 in words is "one hundred ninety-seven million, seven hundred twenty-eight thousand, three hundred ninety-one".