198031021 has 2 divisors, whose sum is σ = 198031022. Its totient is φ = 198031020.

The previous prime is 198031019. The next prime is 198031033. The reversal of 198031021 is 120130891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 121660900 + 76370121 = 11030^2 + 8739^2 .

It is a cyclic number.

It is not a de Polignac number, because 198031021 - 2¹ = 198031019 is a prime.

Together with 198031019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (198031051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99015510 + 99015511.

It is an arithmetic number, because the mean of its divisors is an integer number (99015511).

Almost surely, 2^198031021 is an apocalyptic number.

It is an amenable number.

198031021 is a deficient number, since it is larger than the sum of its proper divisors (1).

198031021 is an equidigital number, since it uses as much as digits as its factorization.

198031021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 198031021 is about 14072.3495195365. The cubic root of 198031021 is about 582.8781053173.

The spelling of 198031021 in words is "one hundred ninety-eight million, thirty-one thousand, twenty-one".