1661605156 has 24 divisors (see below), whose sum is σ = 2939746040. Its totient is φ = 821705472.

The previous prime is 1661605151. The next prime is 1661605171. The reversal of 1661605156 is 6515061661.

It can be written as a sum of positive squares in 4 ways, for example, as 104040000 + 1557565156 = 10200^2 + 39466^2 .

It is not an unprimeable number, because it can be changed into a prime (1661605151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 264160 + ... + 270376.

Almost surely, 2^1661605156 is an apocalyptic number.

It is an amenable number.

1661605156 is a deficient number, since it is larger than the sum of its proper divisors (1278140884).

1661605156 is a wasteful number, since it uses less digits than its factorization.

1661605156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6943 (or 6941 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 37.

The square root of 1661605156 is about 40762.7913175729. The cubic root of 1661605156 is about 1184.4296675671.

The spelling of 1661605156 in words is "one billion, six hundred sixty-one million, six hundred five thousand, one hundred fifty-six".