64519867981 has 4 divisors (see below), whose sum is σ = 65297215872. Its totient is φ = 63742520092.

The previous prime is 64519867949. The next prime is 64519867987. The reversal of 64519867981 is 18976891546.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 64519867981 - 2⁵ = 64519867949 is a prime.

It is a super-2 number, since 2×64519867981² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64519867987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 388673821 + ... + 388673986.

It is an arithmetic number, because the mean of its divisors is an integer number (16324303968).

Almost surely, 2^64519867981 is an apocalyptic number.

It is an amenable number.

64519867981 is a deficient number, since it is larger than the sum of its proper divisors (777347891).

64519867981 is an equidigital number, since it uses as much as digits as its factorization.

64519867981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 777347890.

The product of its digits is 26127360, while the sum is 64.

The spelling of 64519867981 in words is "sixty-four billion, five hundred nineteen million, eight hundred sixty-seven thousand, nine hundred eighty-one".