81568849 has 2 divisors, whose sum is σ = 81568850. Its totient is φ = 81568848.

The previous prime is 81568819. The next prime is 81568859. The reversal of 81568849 is 94886518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 68558400 + 13010449 = 8280^2 + 3607^2 .

It is a cyclic number.

It is not a de Polignac number, because 81568849 - 2¹³ = 81560657 is a prime.

It is a super-3 number, since 3×81568849³ (a number of 25 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (81568819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40784424 + 40784425.

It is an arithmetic number, because the mean of its divisors is an integer number (40784425).

Almost surely, 2^81568849 is an apocalyptic number.

It is an amenable number.

81568849 is a deficient number, since it is larger than the sum of its proper divisors (1).

81568849 is an equidigital number, since it uses as much as digits as its factorization.

81568849 is an evil number, because the sum of its binary digits is even.

The product of its digits is 552960, while the sum is 49.

The square root of 81568849 is about 9031.5474310884. The cubic root of 81568849 is about 433.6853761823.

The spelling of 81568849 in words is "eighty-one million, five hundred sixty-eight thousand, eight hundred forty-nine".