199821421 has 12 divisors (see below), whose sum is σ = 205916256. Its totient is φ = 193877520.

The previous prime is 199821379. The next prime is 199821463. The reversal of 199821421 is 124128991.

199821421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (199821379) and next prime (199821463).

It is a de Polignac number, because none of the positive numbers 2^k-199821421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199821481) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 308520 + ... + 309166.

It is an arithmetic number, because the mean of its divisors is an integer number (17159688).

Almost surely, 2^199821421 is an apocalyptic number.

It is an amenable number.

199821421 is a deficient number, since it is larger than the sum of its proper divisors (6094835).

199821421 is an frugal number, since it uses more digits than its factorization.

199821421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 852 (or 791 counting only the distinct ones).

The product of its digits is 10368, while the sum is 37.

The square root of 199821421 is about 14135.8204926350. The cubic root of 199821421 is about 584.6294397577.

The spelling of 199821421 in words is "one hundred ninety-nine million, eight hundred twenty-one thousand, four hundred twenty-one".