199512021 has 4 divisors (see below), whose sum is σ = 266016032. Its totient is φ = 133008012.

The previous prime is 199511987. The next prime is 199512037. The reversal of 199512021 is 120215991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 199512021 - 2¹⁷ = 199380949 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 199512021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199512421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33252001 + ... + 33252006.

It is an arithmetic number, because the mean of its divisors is an integer number (66504008).

Almost surely, 2^199512021 is an apocalyptic number.

It is an amenable number.

199512021 is a deficient number, since it is larger than the sum of its proper divisors (66504011).

199512021 is an equidigital number, since it uses as much as digits as its factorization.

199512021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66504010.

The product of its (nonzero) digits is 1620, while the sum is 30.

The square root of 199512021 is about 14124.8724242026. The cubic root of 199512021 is about 584.3275405460.

The spelling of 199512021 in words is "one hundred ninety-nine million, five hundred twelve thousand, twenty-one".