1665634720 has 48 divisors (see below), whose sum is σ = 4070765160. Its totient is φ = 643277824.

The previous prime is 1665634693. The next prime is 1665634759. The reversal of 1665634720 is 274365661.

It can be written as a sum of positive squares in 4 ways, for example, as 1641546256 + 24088464 = 40516^2 + 4908^2 .

It is a Harshad number since it is a multiple of its sum of digits (40).

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 7 ways as a sum of consecutive naturals, for example, 174847 + ... + 184126.

Almost surely, 2^1665634720 is an apocalyptic number.

1665634720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1665634720 is an abundant number, since it is smaller than the sum of its proper divisors (2405130440).

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

1665634720 is a wasteful number, since it uses less digits than its factorization.

1665634720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 359017 (or 359009 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 40.

The square root of 1665634720 is about 40812.1883755331. The cubic root of 1665634720 is about 1185.3863493629.

The spelling of 1665634720 in words is "one billion, six hundred sixty-five million, six hundred thirty-four thousand, seven hundred twenty".