1665629681 has 8 divisors (see below), whose sum is σ = 1684387584. Its totient is φ = 1646976240.

The previous prime is 1665629671. The next prime is 1665629687. The reversal of 1665629681 is 1869265661.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 1665629681 - 2¹⁴ = 1665613297 is a prime.

It is a super-2 number, since 2×1665629681² = 5548644468456323522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1665629687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6176 + ... + 58046.

It is an arithmetic number, because the mean of its divisors is an integer number (210548448).

Almost surely, 2^1665629681 is an apocalyptic number.

It is an amenable number.

1665629681 is a deficient number, since it is larger than the sum of its proper divisors (18757903).

1665629681 is a wasteful number, since it uses less digits than its factorization.

1665629681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52231.

The product of its digits is 933120, while the sum is 50.

The square root of 1665629681 is about 40812.1266414775. The cubic root of 1665629681 is about 1185.3851539892.

The spelling of 1665629681 in words is "one billion, six hundred sixty-five million, six hundred twenty-nine thousand, six hundred eighty-one".