16555561 has 8 divisors (see below), whose sum is σ = 18846144. Its totient is φ = 14395920.

The previous prime is 16555543. The next prime is 16555571.

16555561 is nontrivially palindromic in base 10.

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

It is not a de Polignac number, because 16555561 - 2⁵ = 16555529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16555541) 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, 32466 + ... + 32971.

It is an arithmetic number, because the mean of its divisors is an integer number (2355768).

Almost surely, 2^16555561 is an apocalyptic number.

16555561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16555561 is a deficient number, since it is larger than the sum of its proper divisors (2290583).

16555561 is a wasteful number, since it uses less digits than its factorization.

16555561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65471.

The product of its digits is 22500, while the sum is 34.

The square root of 16555561 is about 4068.8525409506. The cubic root of 16555561 is about 254.8676026790.

The spelling of 16555561 in words is "sixteen million, five hundred fifty-five thousand, five hundred sixty-one".