2209661 has 2 divisors, whose sum is σ = 2209662. Its totient is φ = 2209660.

The previous prime is 2209639. The next prime is 2209663. The reversal of 2209661 is 1669022.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1907161 + 302500 = 1381^2 + 550^2 .

It is a cyclic number.

It is not a de Polignac number, because 2209661 - 2¹⁰ = 2208637 is a prime.

It is a Sophie Germain prime.

Together with 2209663, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 2209661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2209663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1104830 + 1104831.

It is an arithmetic number, because the mean of its divisors is an integer number (1104831).

2^2209661 is an apocalyptic number.

It is an amenable number.

2209661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2209661 is an equidigital number, since it uses as much as digits as its factorization.

2209661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 2209661 is about 1486.4928523205. The cubic root of 2209661 is about 130.2492456881.

The spelling of 2209661 in words is "two million, two hundred nine thousand, six hundred sixty-one".