1665016681 has 4 divisors (see below), whose sum is σ = 1677726864. Its totient is φ = 1652306500.

The previous prime is 1665016679. The next prime is 1665016711. The reversal of 1665016681 is 1866105661.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 1665016681 - 2¹ = 1665016679 is a prime.

It is a super-3 number, since 3×1665016681³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1665016181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6354895 + ... + 6355156.

It is an arithmetic number, because the mean of its divisors is an integer number (419431716).

Almost surely, 2^1665016681 is an apocalyptic number.

It is an amenable number.

1665016681 is a deficient number, since it is larger than the sum of its proper divisors (12710183).

1665016681 is a wasteful number, since it uses less digits than its factorization.

1665016681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12710182.

The product of its (nonzero) digits is 51840, while the sum is 40.

The square root of 1665016681 is about 40804.6159276129. The cubic root of 1665016681 is about 1185.2397174480.

The spelling of 1665016681 in words is "one billion, six hundred sixty-five million, sixteen thousand, six hundred eighty-one".