197721 has 10 divisors (see below), whose sum is σ = 295482. Its totient is φ = 131760.

The previous prime is 197713. The next prime is 197741. The reversal of 197721 is 127791.

197721 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 129600 + 68121 = 360^2 + 261^2 .

It is not a de Polignac number, because 197721 - 2³ = 197713 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

197721 is strictly pandigital in base 7.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (197711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1140 + ... + 1301.

2¹⁹⁷⁷²¹ is an apocalyptic number.

It is an amenable number.

197721 is a deficient number, since it is larger than the sum of its proper divisors (97761).

197721 is an equidigital number, since it uses as much as digits as its factorization.

197721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2453 (or 2444 counting only the distinct ones).

The product of its digits is 882, while the sum is 27.

The square root of 197721 is about 444.6582957733. The cubic root of 197721 is about 58.2573777856.

The spelling of 197721 in words is "one hundred ninety-seven thousand, seven hundred twenty-one".