81808201 has 2 divisors, whose sum is σ = 81808202. Its totient is φ = 81808200.

The previous prime is 81808169. The next prime is 81808211. The reversal of 81808201 is 10280818.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81000000 + 808201 = 9000^2 + 899^2 .

It is a cyclic number.

It is not a de Polignac number, because 81808201 - 2⁵ = 81808169 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81808201.

It is not a weakly prime, because it can be changed into another prime (81808211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40904100 + 40904101.

It is an arithmetic number, because the mean of its divisors is an integer number (40904101).

Almost surely, 2^81808201 is an apocalyptic number.

It is an amenable number.

81808201 is a deficient number, since it is larger than the sum of its proper divisors (1).

81808201 is an equidigital number, since it uses as much as digits as its factorization.

81808201 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1024, while the sum is 28.

The square root of 81808201 is about 9044.7886100229. The cubic root of 81808201 is about 434.1091576321.

It can be divided in two parts, 81 and 808201, that multiplied together give a square (65464281 = 8091²).

The spelling of 81808201 in words is "eighty-one million, eight hundred eight thousand, two hundred one".