661755645 has 12 divisors (see below), whose sum is σ = 1147043196. Its totient is φ = 352936320.

The previous prime is 661755643. The next prime is 661755659. The reversal of 661755645 is 546557166.

It can be written as a sum of positive squares in 2 ways, for example, as 435223044 + 226532601 = 20862^2 + 15051^2 .

It is not a de Polignac number, because 661755645 - 2¹ = 661755643 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 14705681 = 661755645 / (6 + 6 + 1 + 7 + 5 + 5 + 6 + 4 + 5).

It is a self number, because there is not a number n which added to its sum of digits gives 661755645.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661755643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7352796 + ... + 7352885.

It is an arithmetic number, because the mean of its divisors is an integer number (95586933).

Almost surely, 2^661755645 is an apocalyptic number.

It is an amenable number.

661755645 is a deficient number, since it is larger than the sum of its proper divisors (485287551).

661755645 is a wasteful number, since it uses less digits than its factorization.

661755645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14705692 (or 14705689 counting only the distinct ones).

The product of its digits is 756000, while the sum is 45.

The square root of 661755645 is about 25724.6116588764. The cubic root of 661755645 is about 871.4300894958.

The spelling of 661755645 in words is "six hundred sixty-one million, seven hundred fifty-five thousand, six hundred forty-five".