64519681 has 2 divisors, whose sum is σ = 64519682. Its totient is φ = 64519680.

The previous prime is 64519657. The next prime is 64519699. The reversal of 64519681 is 18691546.

64519681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45684081 + 18835600 = 6759^2 + 4340^2 .

It is a cyclic number.

It is not a de Polignac number, because 64519681 - 2¹¹ = 64517633 is a prime.

It is a super-2 number, since 2×64519681² = 8325578472683522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (64519781) 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, 32259840 + 32259841.

It is an arithmetic number, because the mean of its divisors is an integer number (32259841).

Almost surely, 2^64519681 is an apocalyptic number.

It is an amenable number.

64519681 is a deficient number, since it is larger than the sum of its proper divisors (1).

64519681 is an equidigital number, since it uses as much as digits as its factorization.

64519681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 40.

The square root of 64519681 is about 8032.4143941906. The cubic root of 64519681 is about 401.0797514693.

The spelling of 64519681 in words is "sixty-four million, five hundred nineteen thousand, six hundred eighty-one".