197908561 has 2 divisors, whose sum is σ = 197908562. Its totient is φ = 197908560.

The previous prime is 197908559. The next prime is 197908573. The reversal of 197908561 is 165809791.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 190854225 + 7054336 = 13815^2 + 2656^2 .

It is a cyclic number.

It is not a de Polignac number, because 197908561 - 2¹ = 197908559 is a prime.

Together with 197908559, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (197902561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 98954280 + 98954281.

It is an arithmetic number, because the mean of its divisors is an integer number (98954281).

Almost surely, 2^197908561 is an apocalyptic number.

It is an amenable number.

197908561 is a deficient number, since it is larger than the sum of its proper divisors (1).

197908561 is an equidigital number, since it uses as much as digits as its factorization.

197908561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 136080, while the sum is 46.

The square root of 197908561 is about 14067.9977608756. The cubic root of 197908561 is about 582.7579322744.

The spelling of 197908561 in words is "one hundred ninety-seven million, nine hundred eight thousand, five hundred sixty-one".