81562081 has 2 divisors, whose sum is σ = 81562082. Its totient is φ = 81562080.

The previous prime is 81562043. The next prime is 81562087. The reversal of 81562081 is 18026518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64883025 + 16679056 = 8055^2 + 4084^2 .

It is a cyclic number.

It is not a de Polignac number, because 81562081 - 2¹⁵ = 81529313 is a prime.

It is a super-2 number, since 2×81562081² = 13304746114101122, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81562087) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40781040 + 40781041.

It is an arithmetic number, because the mean of its divisors is an integer number (40781041).

Almost surely, 2^81562081 is an apocalyptic number.

It is an amenable number.

81562081 is a deficient number, since it is larger than the sum of its proper divisors (1).

81562081 is an equidigital number, since it uses as much as digits as its factorization.

81562081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 81562081 is about 9031.1727366937. The cubic root of 81562081 is about 433.6733811464.

Adding to 81562081 its reverse (18026518), we get a palindrome (99588599).

The spelling of 81562081 in words is "eighty-one million, five hundred sixty-two thousand, eighty-one".