1661512609 has 8 divisors (see below), whose sum is σ = 1681528680. Its totient is φ = 1641526656.

The previous prime is 1661512603. The next prime is 1661512613. The reversal of 1661512609 is 9062151661.

It can be written as a sum of positive squares in 4 ways, for example, as 169390225 + 1492122384 = 13015^2 + 38628^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1661512609 - 2⁷ = 1661512481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661512603) 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 7 ways as a sum of consecutive naturals, for example, 115399 + ... + 128995.

It is an arithmetic number, because the mean of its divisors is an integer number (210191085).

Almost surely, 2^1661512609 is an apocalyptic number.

It is an amenable number.

1661512609 is a deficient number, since it is larger than the sum of its proper divisors (20016071).

1661512609 is a wasteful number, since it uses less digits than its factorization.

1661512609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15059.

The product of its (nonzero) digits is 19440, while the sum is 37.

The square root of 1661512609 is about 40761.6561120865. The cubic root of 1661512609 is about 1184.4076772952.

The spelling of 1661512609 in words is "one billion, six hundred sixty-one million, five hundred twelve thousand, six hundred nine".