187728341221 has 2 divisors, whose sum is σ = 187728341222. Its totient is φ = 187728341220.

The previous prime is 187728341161. The next prime is 187728341267. The reversal of 187728341221 is 122143827781.

It is an a-pointer prime, because the next prime (187728341267) can be obtained adding 187728341221 to its sum of digits (46).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 135894712321 + 51833628900 = 368639^2 + 227670^2 .

It is a cyclic number.

It is not a de Polignac number, because 187728341221 - 2¹⁷ = 187728210149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (187728345221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 93864170610 + 93864170611.

It is an arithmetic number, because the mean of its divisors is an integer number (93864170611).

Almost surely, 2^187728341221 is an apocalyptic number.

It is an amenable number.

187728341221 is a deficient number, since it is larger than the sum of its proper divisors (1).

187728341221 is an equidigital number, since it uses as much as digits as its factorization.

187728341221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 301056, while the sum is 46.

The spelling of 187728341221 in words is "one hundred eighty-seven billion, seven hundred twenty-eight million, three hundred forty-one thousand, two hundred twenty-one".