197856825721 has 3 divisors (see below), whose sum is σ = 197857270533. Its totient is φ = 197856380910.

The previous prime is 197856825707. The next prime is 197856825737. The reversal of 197856825721 is 127528658791.

The square root of 197856825721 is 444811.

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

197856825721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a de Polignac number, because none of the positive numbers 2^k-197856825721 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 197856825721.

It is not an unprimeable number, because it can be changed into a prime (197856829721) 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 2 ways as a sum of consecutive naturals, for example, 222406 + ... + 667216.

It is an arithmetic number, because the mean of its divisors is an integer number (65952423511).

Almost surely, 2^197856825721 is an apocalyptic number.

197856825721 is the 444811-st square number.

197856825721 is the 222406-th centered octagonal number.

It is an amenable number.

197856825721 is a deficient number, since it is larger than the sum of its proper divisors (444812).

197856825721 is an frugal number, since it uses more digits than its factorization.

197856825721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 889622 (or 444811 counting only the distinct ones).

The product of its digits is 16934400, while the sum is 61.

The spelling of 197856825721 in words is "one hundred ninety-seven billion, eight hundred fifty-six million, eight hundred twenty-five thousand, seven hundred twenty-one".