197981118721 has 4 divisors (see below), whose sum is σ = 206588993472. Its totient is φ = 189373243972.

The previous prime is 197981118719. The next prime is 197981118749. The reversal of 197981118721 is 127811189791.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 127811189791 = 5953 ⋅21470047.

It is a cyclic number.

It is not a de Polignac number, because 197981118721 - 2¹ = 197981118719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (197981118781) 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, 4303937341 + ... + 4303937386.

It is an arithmetic number, because the mean of its divisors is an integer number (51647248368).

Almost surely, 2^197981118721 is an apocalyptic number.

It is an amenable number.

197981118721 is a deficient number, since it is larger than the sum of its proper divisors (8607874751).

197981118721 is an equidigital number, since it uses as much as digits as its factorization.

197981118721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8607874750.

The product of its digits is 508032, while the sum is 55.

The spelling of 197981118721 in words is "one hundred ninety-seven billion, nine hundred eighty-one million, one hundred eighteen thousand, seven hundred twenty-one".