197736821 has 2 divisors, whose sum is σ = 197736822. Its totient is φ = 197736820.

The previous prime is 197736739. The next prime is 197736823. The reversal of 197736821 is 128637791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 110986225 + 86750596 = 10535^2 + 9314^2 .

It is an emirp because it is prime and its reverse (128637791) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 197736821 - 2¹⁴ = 197720437 is a prime.

It is a Sophie Germain prime.

Together with 197736823, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (197736823) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 98868410 + 98868411.

It is an arithmetic number, because the mean of its divisors is an integer number (98868411).

Almost surely, 2^197736821 is an apocalyptic number.

It is an amenable number.

197736821 is a deficient number, since it is larger than the sum of its proper divisors (1).

197736821 is an equidigital number, since it uses as much as digits as its factorization.

197736821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 127008, while the sum is 44.

The square root of 197736821 is about 14061.8925113229. The cubic root of 197736821 is about 582.5893160027.

The spelling of 197736821 in words is "one hundred ninety-seven million, seven hundred thirty-six thousand, eight hundred twenty-one".