199621 has 2 divisors, whose sum is σ = 199622. Its totient is φ = 199620.

The previous prime is 199603. The next prime is 199637. The reversal of 199621 is 126991.

199621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 148996 + 50625 = 386^2 + 225^2 .

It is a cyclic number.

It is not a de Polignac number, because 199621 - 2⁹ = 199109 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a nialpdrome in base 12.

It is a self number, because there is not a number n which added to its sum of digits gives 199621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99810 + 99811.

It is an arithmetic number, because the mean of its divisors is an integer number (99811).

2¹⁹⁹⁶²¹ is an apocalyptic number.

It is an amenable number.

199621 is a deficient number, since it is larger than the sum of its proper divisors (1).

199621 is an equidigital number, since it uses as much as digits as its factorization.

199621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 972, while the sum is 28.

The square root of 199621 is about 446.7896596834. The cubic root of 199621 is about 58.4433913151.

It can be divided in two parts, 199 and 621, that added together give a triangular number (820 = T₄₀).

The spelling of 199621 in words is "one hundred ninety-nine thousand, six hundred twenty-one".