198219921 has 16 divisors (see below), whose sum is σ = 273358848. Its totient is φ = 127630800.

The previous prime is 198219883. The next prime is 198219937. The reversal of 198219921 is 129912891.

It is not a de Polignac number, because 198219921 - 2⁷ = 198219793 is a prime.

It is a super-2 number, since 2×198219921² = 78582274162492482, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (198229921) 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, 52776 + ... + 56406.

It is an arithmetic number, because the mean of its divisors is an integer number (17084928).

Almost surely, 2^198219921 is an apocalyptic number.

It is an amenable number.

198219921 is a deficient number, since it is larger than the sum of its proper divisors (75138927).

198219921 is a wasteful number, since it uses less digits than its factorization.

198219921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4252.

The product of its digits is 23328, while the sum is 42.

The square root of 198219921 is about 14079.0596632019. The cubic root of 198219921 is about 583.0633804702.

The spelling of 198219921 in words is "one hundred ninety-eight million, two hundred nineteen thousand, nine hundred twenty-one".