1611666561 has 8 divisors (see below), whose sum is σ = 2222988480. Its totient is φ = 1037394512.

The previous prime is 1611666523. The next prime is 1611666571. The reversal of 1611666561 is 1656661161.

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 1611666561 - 2¹⁰ = 1611665537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1611666571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9262365 + ... + 9262538.

It is an arithmetic number, because the mean of its divisors is an integer number (277873560).

Almost surely, 2^1611666561 is an apocalyptic number.

It is an amenable number.

1611666561 is a deficient number, since it is larger than the sum of its proper divisors (611321919).

1611666561 is a wasteful number, since it uses less digits than its factorization.

1611666561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18524935.

The product of its digits is 38880, while the sum is 39.

The square root of 1611666561 is about 40145.5671400966. The cubic root of 1611666561 is about 1172.4429829688.

The spelling of 1611666561 in words is "one billion, six hundred eleven million, six hundred sixty-six thousand, five hundred sixty-one".