209420191 has 8 divisors (see below), whose sum is σ = 214487504. Its totient is φ = 204361920.

The previous prime is 209420179. The next prime is 209420201. The reversal of 209420191 is 191024902.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 209420191 - 2⁷ = 209420063 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 (209420131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78715 + ... + 81331.

It is an arithmetic number, because the mean of its divisors is an integer number (26810938).

Almost surely, 2^209420191 is an apocalyptic number.

209420191 is a deficient number, since it is larger than the sum of its proper divisors (5067313).

209420191 is a wasteful number, since it uses less digits than its factorization.

209420191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4521.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 209420191 is about 14471.3576073567. The cubic root of 209420191 is about 593.8446530393.

The spelling of 209420191 in words is "two hundred nine million, four hundred twenty thousand, one hundred ninety-one".