1660561505 has 4 divisors (see below), whose sum is σ = 1992673812. Its totient is φ = 1328449200.

The previous prime is 1660561501. The next prime is 1660561537. The reversal of 1660561505 is 5051650661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5051650661 = 35437 ⋅142553.

It can be written as a sum of positive squares in 2 ways, for example, as 347151424 + 1313410081 = 18632^2 + 36241^2 .

It is not a de Polignac number, because 1660561505 - 2² = 1660561501 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1660561501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166056146 + ... + 166056155.

It is an arithmetic number, because the mean of its divisors is an integer number (498168453).

Almost surely, 2^1660561505 is an apocalyptic number.

It is an amenable number.

1660561505 is a deficient number, since it is larger than the sum of its proper divisors (332112307).

1660561505 is an equidigital number, since it uses as much as digits as its factorization.

1660561505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332112306.

The product of its (nonzero) digits is 27000, while the sum is 35.

The square root of 1660561505 is about 40749.9877914092. The cubic root of 1660561505 is about 1184.1816362991.

The spelling of 1660561505 in words is "one billion, six hundred sixty million, five hundred sixty-one thousand, five hundred five".