100555561 has 4 divisors (see below), whose sum is σ = 106470612. Its totient is φ = 94640512.

The previous prime is 100555523. The next prime is 100555571. The reversal of 100555561 is 165555001.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 52113961 + 48441600 = 7219^2 + 6960^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-100555561 is a prime.

It is a super-2 number, since 2×100555561² = 20222841696049442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (100555571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2957500 + ... + 2957533.

It is an arithmetic number, because the mean of its divisors is an integer number (26617653).

Almost surely, 2^100555561 is an apocalyptic number.

It is an amenable number.

100555561 is a deficient number, since it is larger than the sum of its proper divisors (5915051).

100555561 is an equidigital number, since it uses as much as digits as its factorization.

100555561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5915050.

The product of its (nonzero) digits is 3750, while the sum is 28.

The square root of 100555561 is about 10027.7395757967. The cubic root of 100555561 is about 465.0168583706.

The spelling of 100555561 in words is "one hundred million, five hundred fifty-five thousand, five hundred sixty-one".