1661305173 has 8 divisors (see below), whose sum is σ = 2416443936. Its totient is φ = 1006851600.

The previous prime is 1661305123. The next prime is 1661305183. The reversal of 1661305173 is 3715031661.

It is a happy number.

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

It is not a de Polignac number, because 1661305173 - 2⁸ = 1661304917 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 50342581 = 1661305173 / (1 + 6 + 6 + 1 + 3 + 0 + 5 + 1 + 7 + 3).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661305123) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25171258 + ... + 25171323.

It is an arithmetic number, because the mean of its divisors is an integer number (302055492).

Almost surely, 2^1661305173 is an apocalyptic number.

It is an amenable number.

1661305173 is a deficient number, since it is larger than the sum of its proper divisors (755138763).

1661305173 is a wasteful number, since it uses less digits than its factorization.

1661305173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50342595.

The product of its (nonzero) digits is 11340, while the sum is 33.

The square root of 1661305173 is about 40759.1115334964. Note that the first 3 decimals coincide. The cubic root of 1661305173 is about 1184.3583850590.

The spelling of 1661305173 in words is "one billion, six hundred sixty-one million, three hundred five thousand, one hundred seventy-three".