1665551109 has 4 divisors (see below), whose sum is σ = 2220734816. Its totient is φ = 1110367404.

The previous prime is 1665551093. The next prime is 1665551117. The reversal of 1665551109 is 9011555661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9011555661 = 3 ⋅3003851887.

It is not a de Polignac number, because 1665551109 - 2⁴ = 1665551093 is a prime.

It is a super-2 number, since 2×1665551109² = 5548120993382259762, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665551119) 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 3 ways as a sum of consecutive naturals, for example, 277591849 + ... + 277591854.

It is an arithmetic number, because the mean of its divisors is an integer number (555183704).

Almost surely, 2^1665551109 is an apocalyptic number.

It is an amenable number.

1665551109 is a deficient number, since it is larger than the sum of its proper divisors (555183707).

1665551109 is an equidigital number, since it uses as much as digits as its factorization.

1665551109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 555183706.

The product of its (nonzero) digits is 40500, while the sum is 39.

The square root of 1665551109 is about 40811.1640240756. The cubic root of 1665551109 is about 1185.3665144825.

The spelling of 1665551109 in words is "one billion, six hundred sixty-five million, five hundred fifty-one thousand, one hundred nine".