181487928221 has 2 divisors, whose sum is σ = 181487928222. Its totient is φ = 181487928220.

The previous prime is 181487928191. The next prime is 181487928239. The reversal of 181487928221 is 122829784181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 181487928196 + 25 = 426014^2 + 5^2 .

It is a cyclic number.

It is not a de Polignac number, because 181487928221 - 2¹⁸ = 181487666077 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181487928421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90743964110 + 90743964111.

It is an arithmetic number, because the mean of its divisors is an integer number (90743964111).

Almost surely, 2^181487928221 is an apocalyptic number.

It is an amenable number.

181487928221 is a deficient number, since it is larger than the sum of its proper divisors (1).

181487928221 is an equidigital number, since it uses as much as digits as its factorization.

181487928221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1032192, while the sum is 53.

The spelling of 181487928221 in words is "one hundred eighty-one billion, four hundred eighty-seven million, nine hundred twenty-eight thousand, two hundred twenty-one".