81508201 has 2 divisors, whose sum is σ = 81508202. Its totient is φ = 81508200.

The previous prime is 81508181. The next prime is 81508237. The reversal of 81508201 is 10280518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81432576 + 75625 = 9024^2 + 275^2 .

It is a cyclic number.

It is not a de Polignac number, because 81508201 - 2⁷ = 81508073 is a prime.

It is not a weakly prime, because it can be changed into another prime (81508291) 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, 40754100 + 40754101.

It is an arithmetic number, because the mean of its divisors is an integer number (40754101).

Almost surely, 2^81508201 is an apocalyptic number.

It is an amenable number.

81508201 is a deficient number, since it is larger than the sum of its proper divisors (1).

81508201 is an equidigital number, since it uses as much as digits as its factorization.

81508201 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 640, while the sum is 25.

The square root of 81508201 is about 9028.1892425890. The cubic root of 81508201 is about 433.5778650739.

Adding to 81508201 its reverse (10280518), we get a palindrome (91788719).

The spelling of 81508201 in words is "eighty-one million, five hundred eight thousand, two hundred one".