661109 has 2 divisors, whose sum is σ = 661110. Its totient is φ = 661108.

The previous prime is 661103. The next prime is 661117. The reversal of 661109 is 901166.

661109 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 483025 + 178084 = 695^2 + 422^2 .

It is a cyclic number.

It is not a de Polignac number, because 661109 - 2⁴ = 661093 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330554 + 330555.

It is an arithmetic number, because the mean of its divisors is an integer number (330555).

2⁶⁶¹¹⁰⁹ is an apocalyptic number.

It is an amenable number.

661109 is a deficient number, since it is larger than the sum of its proper divisors (1).

661109 is an equidigital number, since it uses as much as digits as its factorization.

661109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 661109 is about 813.0860963022. The cubic root of 661109 is about 87.1146153091.

The spelling of 661109 in words is "six hundred sixty-one thousand, one hundred nine".