197945797921 has 9 divisors (see below), whose sum is σ = 200234953011. Its totient is φ = 195682535664.

The previous prime is 197945797883. The next prime is 197945797937. The reversal of 197945797921 is 129797549791.

The square root of 197945797921 is 444911.

It is a perfect power (a square), and thus also a powerful number.

197945797921 is digitally balanced in base 2, 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., 38009791521 + 159936006400 = 194961^2 + 399920^2 .

It is not a de Polignac number, because 197945797921 - 2¹⁹ = 197945273633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (197945797961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 39594580 + ... + 39599578.

Almost surely, 2^197945797921 is an apocalyptic number.

197945797921 is the 444911-st square number.

197945797921 is the 222456-th centered octagonal number.

It is an amenable number.

197945797921 is a deficient number, since it is larger than the sum of its proper divisors (2289155090).

197945797921 is an frugal number, since it uses more digits than its factorization.

197945797921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10176 (or 5088 counting only the distinct ones).

The product of its digits is 90016920, while the sum is 70.

It can be divided in two parts, 19794579 and 7921, that added together give a square (19802500 = 4450²).

The spelling of 197945797921 in words is "one hundred ninety-seven billion, nine hundred forty-five million, seven hundred ninety-seven thousand, nine hundred twenty-one".