198120021 has 16 divisors (see below), whose sum is σ = 288445440. Its totient is φ = 119959920.

The previous prime is 198120019. The next prime is 198120031. The reversal of 198120021 is 120021891.

It is not a de Polignac number, because 198120021 - 2¹ = 198120019 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 198119973 and 198120000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (198120031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44850 + ... + 49068.

It is an arithmetic number, because the mean of its divisors is an integer number (18027840).

Almost surely, 2^198120021 is an apocalyptic number.

198120021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

198120021 is a deficient number, since it is larger than the sum of its proper divisors (90325419).

198120021 is a wasteful number, since it uses less digits than its factorization.

198120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5656.

The product of its (nonzero) digits is 288, while the sum is 24.

The square root of 198120021 is about 14075.5113939068. The cubic root of 198120021 is about 582.9654121470.

The spelling of 198120021 in words is "one hundred ninety-eight million, one hundred twenty thousand, twenty-one".