209794021 has 8 divisors (see below), whose sum is σ = 210987000. Its totient is φ = 208605120.

The previous prime is 209794001. The next prime is 209794027. The reversal of 209794021 is 120497902.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 134884996 + 74909025 = 11614^2 + 8655^2 .

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 209794021 - 2¹⁷ = 209662949 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 (209794027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 177051 + ... + 178231.

It is an arithmetic number, because the mean of its divisors is an integer number (26373375).

Almost surely, 2^209794021 is an apocalyptic number.

It is an amenable number.

209794021 is a deficient number, since it is larger than the sum of its proper divisors (1192979).

209794021 is a wasteful number, since it uses less digits than its factorization.

209794021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2039.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 209794021 is about 14484.2680519245. The cubic root of 209794021 is about 594.1977947030.

The spelling of 209794021 in words is "two hundred nine million, seven hundred ninety-four thousand, twenty-one".