661665549 has 8 divisors (see below), whose sum is σ = 883586880. Its totient is φ = 440427296.

The previous prime is 661665509. The next prime is 661665559. The reversal of 661665549 is 945566166.

661665549 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 661665549 - 2¹⁵ = 661632781 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 661665498 and 661665507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661665509) 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, 168504 + ... + 172385.

It is an arithmetic number, because the mean of its divisors is an integer number (110448360).

Almost surely, 2^661665549 is an apocalyptic number.

It is an amenable number.

661665549 is a deficient number, since it is larger than the sum of its proper divisors (221921331).

661665549 is a wasteful number, since it uses less digits than its factorization.

661665549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 341539.

The product of its digits is 1166400, while the sum is 48.

The square root of 661665549 is about 25722.8604358069. The cubic root of 661665549 is about 871.3905401902.

The spelling of 661665549 in words is "six hundred sixty-one million, six hundred sixty-five thousand, five hundred forty-nine".