1661545361 has 12 divisors (see below), whose sum is σ = 1954540260. Its totient is φ = 1408176000.

The previous prime is 1661545351. The next prime is 1661545367. The reversal of 1661545361 is 1635451661.

It can be written as a sum of positive squares in 2 ways, for example, as 391050625 + 1270494736 = 19775^2 + 35644^2 .

It is not a de Polignac number, because 1661545361 - 2⁶ = 1661545297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661545367) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 186140 + ... + 194861.

It is an arithmetic number, because the mean of its divisors is an integer number (162878355).

Almost surely, 2^1661545361 is an apocalyptic number.

It is an amenable number.

1661545361 is a deficient number, since it is larger than the sum of its proper divisors (292994899).

1661545361 is an equidigital number, since it uses as much as digits as its factorization.

1661545361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 381104 (or 381097 counting only the distinct ones).

The product of its digits is 64800, while the sum is 38.

The square root of 1661545361 is about 40762.0578602209. The cubic root of 1661545361 is about 1184.4154596547.

The spelling of 1661545361 in words is "one billion, six hundred sixty-one million, five hundred forty-five thousand, three hundred sixty-one".