1665005661 has 24 divisors (see below), whose sum is σ = 2694560544. Its totient is φ = 981819360.

The previous prime is 1665005633. The next prime is 1665005731.

1665005661 is nontrivially palindromic in base 10.

It is a de Polignac number, because none of the positive numbers 2^k-1665005661 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665005611) 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 23 ways as a sum of consecutive naturals, for example, 223611 + ... + 230936.

It is an arithmetic number, because the mean of its divisors is an integer number (112273356).

Almost surely, 2^1665005661 is an apocalyptic number.

1665005661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1665005661 is a deficient number, since it is larger than the sum of its proper divisors (1029554883).

1665005661 is a wasteful number, since it uses less digits than its factorization.

1665005661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 454601 (or 454598 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 36.

The square root of 1665005661 is about 40804.4808936470. The cubic root of 1665005661 is about 1185.2371025852.

The spelling of 1665005661 in words is "one billion, six hundred sixty-five million, five thousand, six hundred sixty-one".