1661606505 has 24 divisors (see below), whose sum is σ = 3101666568. Its totient is φ = 818021376.

The previous prime is 1661606497. The next prime is 1661606587. The reversal of 1661606505 is 5056061661.

It can be written as a sum of positive squares in 4 ways, for example, as 23299929 + 1638306576 = 4827^2 + 40476^2 .

It is not a de Polignac number, because 1661606505 - 2³ = 1661606497 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1661606505.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1419592 + ... + 1420761.

It is an arithmetic number, because the mean of its divisors is an integer number (129236107).

Almost surely, 2^1661606505 is an apocalyptic number.

1661606505 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1661606505 is a deficient number, since it is larger than the sum of its proper divisors (1440060063).

1661606505 is a wasteful number, since it uses less digits than its factorization.

1661606505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2840377 (or 2840374 counting only the distinct ones).

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

The square root of 1661606505 is about 40762.8078645228. The cubic root of 1661606505 is about 1184.4299880996.

The spelling of 1661606505 in words is "one billion, six hundred sixty-one million, six hundred six thousand, five hundred five".