189816421 has 2 divisors, whose sum is σ = 189816422. Its totient is φ = 189816420.

The previous prime is 189816391. The next prime is 189816443. The reversal of 189816421 is 124618981.

189816421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 187964100 + 1852321 = 13710^2 + 1361^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-189816421 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 (189816481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94908210 + 94908211.

It is an arithmetic number, because the mean of its divisors is an integer number (94908211).

Almost surely, 2^189816421 is an apocalyptic number.

It is an amenable number.

189816421 is a deficient number, since it is larger than the sum of its proper divisors (1).

189816421 is an equidigital number, since it uses as much as digits as its factorization.

189816421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27648, while the sum is 40.

The square root of 189816421 is about 13777.3880325699. The cubic root of 189816421 is about 574.7044944098.

The spelling of 189816421 in words is "one hundred eighty-nine million, eight hundred sixteen thousand, four hundred twenty-one".