188866561 has 4 divisors (see below), whose sum is σ = 203394772. Its totient is φ = 174338352.

The previous prime is 188866529. The next prime is 188866567. The reversal of 188866561 is 165668881.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 165668881 = 7 ⋅23666983.

It can be written as a sum of positive squares in 2 ways, for example, as 30735936 + 158130625 = 5544^2 + 12575^2 .

It is a cyclic number.

It is not a de Polignac number, because 188866561 - 2⁵ = 188866529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (188866567) 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, 7264086 + ... + 7264111.

It is an arithmetic number, because the mean of its divisors is an integer number (50848693).

Almost surely, 2^188866561 is an apocalyptic number.

It is an amenable number.

188866561 is a deficient number, since it is larger than the sum of its proper divisors (14528211).

188866561 is a wasteful number, since it uses less digits than its factorization.

188866561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14528210.

The product of its digits is 552960, while the sum is 49.

The square root of 188866561 is about 13742.8730984463. The cubic root of 188866561 is about 573.7442650322.

The spelling of 188866561 in words is "one hundred eighty-eight million, eight hundred sixty-six thousand, five hundred sixty-one".