1665166644 has 36 divisors (see below), whose sum is σ = 4246430916. Its totient is φ = 550142208.

The previous prime is 1665166603. The next prime is 1665166651. The reversal of 1665166644 is 4466615661.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 185995044 + 1479171600 = 13638^2 + 38460^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a self number, because there is not a number n which added to its sum of digits gives 1665166644.

It is a congruent number.

It is an unprimeable number.

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, 200599 + ... + 208734.

Almost surely, 2^1665166644 is an apocalyptic number.

It is an amenable number.

1665166644 is an abundant number, since it is smaller than the sum of its proper divisors (2581264272).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1665166644 is a wasteful number, since it uses less digits than its factorization.

1665166644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 409456 (or 409451 counting only the distinct ones).

The product of its digits is 622080, while the sum is 45.

The square root of 1665166644 is about 40806.4534602065. The cubic root of 1665166644 is about 1185.2753000280.

The spelling of 1665166644 in words is "one billion, six hundred sixty-five million, one hundred sixty-six thousand, six hundred forty-four".