81896569 has 2 divisors, whose sum is σ = 81896570. Its totient is φ = 81896568.

The previous prime is 81896567. The next prime is 81896597. The reversal of 81896569 is 96569818.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42055225 + 39841344 = 6485^2 + 6312^2 .

It is a cyclic number.

It is not a de Polignac number, because 81896569 - 2¹ = 81896567 is a prime.

It is a super-2 number, since 2×81896569² = 13414096027943522, which contains 22 as substring.

Together with 81896567, it forms a pair of twin primes.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (81896567) 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, 40948284 + 40948285.

It is an arithmetic number, because the mean of its divisors is an integer number (40948285).

Almost surely, 2^81896569 is an apocalyptic number.

It is an amenable number.

81896569 is a deficient number, since it is larger than the sum of its proper divisors (1).

81896569 is an equidigital number, since it uses as much as digits as its factorization.

81896569 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 933120, while the sum is 52.

The square root of 81896569 is about 9049.6723145095. The cubic root of 81896569 is about 434.2654074677.

The spelling of 81896569 in words is "eighty-one million, eight hundred ninety-six thousand, five hundred sixty-nine".