100665561 has 8 divisors (see below), whose sum is σ = 134267200. Its totient is φ = 67087152.

The previous prime is 100665559. The next prime is 100665563. The reversal of 100665561 is 165566001.

It is an interprime number because it is at equal distance from previous prime (100665559) and next prime (100665563).

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

It is not a de Polignac number, because 100665561 - 2¹ = 100665559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (100665563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13140 + ... + 19338.

It is an arithmetic number, because the mean of its divisors is an integer number (16783400).

Almost surely, 2^100665561 is an apocalyptic number.

It is an amenable number.

100665561 is a deficient number, since it is larger than the sum of its proper divisors (33601639).

100665561 is an equidigital number, since it uses as much as digits as its factorization.

100665561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11615.

The product of its (nonzero) digits is 5400, while the sum is 30.

The square root of 100665561 is about 10033.2228620718. Note that the first 3 decimals coincide. The cubic root of 100665561 is about 465.1863607272.

The spelling of 100665561 in words is "one hundred million, six hundred sixty-five thousand, five hundred sixty-one".