188445661 has 2 divisors, whose sum is σ = 188445662. Its totient is φ = 188445660.

The previous prime is 188445659. The next prime is 188445709. The reversal of 188445661 is 166544881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 148376761 + 40068900 = 12181^2 + 6330^2 .

It is a cyclic number.

It is not a de Polignac number, because 188445661 - 2¹ = 188445659 is a prime.

Together with 188445659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (188445611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94222830 + 94222831.

It is an arithmetic number, because the mean of its divisors is an integer number (94222831).

Almost surely, 2^188445661 is an apocalyptic number.

It is an amenable number.

188445661 is a deficient number, since it is larger than the sum of its proper divisors (1).

188445661 is an equidigital number, since it uses as much as digits as its factorization.

188445661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 184320, while the sum is 43.

The square root of 188445661 is about 13727.5511654483. The cubic root of 188445661 is about 573.3177406597.

The spelling of 188445661 in words is "one hundred eighty-eight million, four hundred forty-five thousand, six hundred sixty-one".