209072661 has 24 divisors (see below), whose sum is σ = 326377440. Its totient is φ = 118696032.

The previous prime is 209072641. The next prime is 209072663. The reversal of 209072661 is 166270902.

It is not a de Polignac number, because 209072661 - 2⁶ = 209072597 is a prime.

It is a super-2 number, since 2×209072661² = 87422755155241842, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209072663) 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 23 ways as a sum of consecutive naturals, for example, 18550 + ... + 27608.

It is an arithmetic number, because the mean of its divisors is an integer number (13599060).

Almost surely, 2^209072661 is an apocalyptic number.

209072661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

209072661 is a deficient number, since it is larger than the sum of its proper divisors (117304779).

209072661 is a wasteful number, since it uses less digits than its factorization.

209072661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9233 (or 9226 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 209072661 is about 14459.3451096514. The cubic root of 209072661 is about 593.5159787480.

The spelling of 209072661 in words is "two hundred nine million, seventy-two thousand, six hundred sixty-one".