100665661 has 4 divisors (see below), whose sum is σ = 101458432. Its totient is φ = 99872892.

The previous prime is 100665659. The next prime is 100665679. The reversal of 100665661 is 166566001.

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: 166566001 = 7 ⋅23795143.

It is a cyclic number.

It is not a de Polignac number, because 100665661 - 2¹ = 100665659 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100665601) 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, 396195 + ... + 396448.

It is an arithmetic number, because the mean of its divisors is an integer number (25364608).

Almost surely, 2^100665661 is an apocalyptic number.

It is an amenable number.

100665661 is a deficient number, since it is larger than the sum of its proper divisors (792771).

100665661 is an equidigital number, since it uses as much as digits as its factorization.

100665661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 792770.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 100665661 is about 10033.2278455141. The cubic root of 100665661 is about 465.1865147641.

The spelling of 100665661 in words is "one hundred million, six hundred sixty-five thousand, six hundred sixty-one".