199190021 has 2 divisors, whose sum is σ = 199190022. Its totient is φ = 199190020.

The previous prime is 199189993. The next prime is 199190027. The reversal of 199190021 is 120091991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 190716100 + 8473921 = 13810^2 + 2911^2 .

It is a cyclic number.

It is not a de Polignac number, because 199190021 - 2¹⁸ = 198927877 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 199190021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199190027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99595010 + 99595011.

It is an arithmetic number, because the mean of its divisors is an integer number (99595011).

Almost surely, 2^199190021 is an apocalyptic number.

It is an amenable number.

199190021 is a deficient number, since it is larger than the sum of its proper divisors (1).

199190021 is an equidigital number, since it uses as much as digits as its factorization.

199190021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458, while the sum is 32.

The square root of 199190021 is about 14113.4694884001. The cubic root of 199190021 is about 584.0130151678.

The spelling of 199190021 in words is "one hundred ninety-nine million, one hundred ninety thousand, twenty-one".