198271921 has 2 divisors, whose sum is σ = 198271922. Its totient is φ = 198271920.

The previous prime is 198271903. The next prime is 198271933. The reversal of 198271921 is 129172891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 103306896 + 94965025 = 10164^2 + 9745^2 .

It is an emirp because it is prime and its reverse (129172891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 198271921 - 2⁷ = 198271793 is a prime.

It is not a weakly prime, because it can be changed into another prime (198271421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99135960 + 99135961.

It is an arithmetic number, because the mean of its divisors is an integer number (99135961).

Almost surely, 2^198271921 is an apocalyptic number.

It is an amenable number.

198271921 is a deficient number, since it is larger than the sum of its proper divisors (1).

198271921 is an equidigital number, since it uses as much as digits as its factorization.

198271921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 40.

The square root of 198271921 is about 14080.9062563459. The cubic root of 198271921 is about 583.1143619671.

The spelling of 198271921 in words is "one hundred ninety-eight million, two hundred seventy-one thousand, nine hundred twenty-one".