1661303605 has 16 divisors (see below), whose sum is σ = 2148323184. Its totient is φ = 1226004480.

The previous prime is 1661303591. The next prime is 1661303669. The reversal of 1661303605 is 5063031661.

It can be written as a sum of positive squares in 8 ways, for example, as 50324836 + 1610978769 = 7094^2 + 40137^2 .

It is not a de Polignac number, because 1661303605 - 2¹³ = 1661295413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 102775 + ... + 117835.

It is an arithmetic number, because the mean of its divisors is an integer number (134270199).

Almost surely, 2^1661303605 is an apocalyptic number.

It is an amenable number.

1661303605 is a deficient number, since it is larger than the sum of its proper divisors (487019579).

1661303605 is a wasteful number, since it uses less digits than its factorization.

1661303605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16776.

The product of its (nonzero) digits is 9720, while the sum is 31.

The square root of 1661303605 is about 40759.0922985289. The cubic root of 1661303605 is about 1184.3580124454.

The spelling of 1661303605 in words is "one billion, six hundred sixty-one million, three hundred three thousand, six hundred five".