198921971 has 2 divisors, whose sum is σ = 198921972. Its totient is φ = 198921970.

The previous prime is 198921959. The next prime is 198921977. The reversal of 198921971 is 179129891.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 198921971 - 2¹⁸ = 198659827 is a prime.

It is not a weakly prime, because it can be changed into another prime (198921977) 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 as a sum of consecutive naturals, namely, 99460985 + 99460986.

It is an arithmetic number, because the mean of its divisors is an integer number (99460986).

Almost surely, 2^198921971 is an apocalyptic number.

198921971 is a deficient number, since it is larger than the sum of its proper divisors (1).

198921971 is an equidigital number, since it uses as much as digits as its factorization.

198921971 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81648, while the sum is 47.

The square root of 198921971 is about 14103.9700439273. The cubic root of 198921971 is about 583.7509288089.

The spelling of 198921971 in words is "one hundred ninety-eight million, nine hundred twenty-one thousand, nine hundred seventy-one".