209690921 has 8 divisors (see below), whose sum is σ = 229255488. Its totient is φ = 190210000.

The previous prime is 209690917. The next prime is 209690941. The reversal of 209690921 is 129096902.

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 209690921 - 2² = 209690917 is a prime.

It is not an unprimeable number, because it can be changed into a prime (209690941) 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, 15605 + ... + 25746.

It is an arithmetic number, because the mean of its divisors is an integer number (28656936).

Almost surely, 2^209690921 is an apocalyptic number.

It is an amenable number.

209690921 is a deficient number, since it is larger than the sum of its proper divisors (19564567).

209690921 is a wasteful number, since it uses less digits than its factorization.

209690921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41823.

The product of its (nonzero) digits is 17496, while the sum is 38.

The square root of 209690921 is about 14480.7085807291. The cubic root of 209690921 is about 594.1004423405.

The spelling of 209690921 in words is "two hundred nine million, six hundred ninety thousand, nine hundred twenty-one".