197851561 has 2 divisors, whose sum is σ = 197851562. Its totient is φ = 197851560.

The previous prime is 197851553. The next prime is 197851583. The reversal of 197851561 is 165158791.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 190992400 + 6859161 = 13820^2 + 2619^2 .

It is a cyclic number.

It is not a de Polignac number, because 197851561 - 2³ = 197851553 is a prime.

It is not a weakly prime, because it can be changed into another prime (197851501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 98925780 + 98925781.

It is an arithmetic number, because the mean of its divisors is an integer number (98925781).

Almost surely, 2^197851561 is an apocalyptic number.

It is an amenable number.

197851561 is a deficient number, since it is larger than the sum of its proper divisors (1).

197851561 is an equidigital number, since it uses as much as digits as its factorization.

197851561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 75600, while the sum is 43.

The square root of 197851561 is about 14065.9717403385. The cubic root of 197851561 is about 582.7019798496.

The spelling of 197851561 in words is "one hundred ninety-seven million, eight hundred fifty-one thousand, five hundred sixty-one".