188081821 has 2 divisors, whose sum is σ = 188081822. Its totient is φ = 188081820.

The previous prime is 188081771. The next prime is 188081843. The reversal of 188081821 is 128180881.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 139570596 + 48511225 = 11814^2 + 6965^2 .

It is an emirp because it is prime and its reverse (128180881) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 188081821 - 2²⁷ = 53864093 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (188081891) 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 as a sum of consecutive naturals, namely, 94040910 + 94040911.

It is an arithmetic number, because the mean of its divisors is an integer number (94040911).

Almost surely, 2^188081821 is an apocalyptic number.

It is an amenable number.

188081821 is a deficient number, since it is larger than the sum of its proper divisors (1).

188081821 is an equidigital number, since it uses as much as digits as its factorization.

188081821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8192, while the sum is 37.

The square root of 188081821 is about 13714.2925810995. The cubic root of 188081821 is about 572.9485266766.

The spelling of 188081821 in words is "one hundred eighty-eight million, eighty-one thousand, eight hundred twenty-one".