6642664981 has 2 divisors, whose sum is σ = 6642664982. Its totient is φ = 6642664980.

The previous prime is 6642664969. The next prime is 6642665129. The reversal of 6642664981 is 1894662466.

It is a happy number.

6642664981 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5641512100 + 1001152881 = 75110^2 + 31641^2 .

It is a cyclic number.

It is not a de Polignac number, because 6642664981 - 2²⁵ = 6609110549 is a prime.

It is a super-2 number, since 2×6642664981² = 88249996099607460722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6642664181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3321332490 + 3321332491.

It is an arithmetic number, because the mean of its divisors is an integer number (3321332491).

Almost surely, 2^6642664981 is an apocalyptic number.

It is an amenable number.

6642664981 is a deficient number, since it is larger than the sum of its proper divisors (1).

6642664981 is an equidigital number, since it uses as much as digits as its factorization.

6642664981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2985984, while the sum is 52.

The square root of 6642664981 is about 81502.5458559424. The cubic root of 6642664981 is about 1879.8106966664.

The spelling of 6642664981 in words is "six billion, six hundred forty-two million, six hundred sixty-four thousand, nine hundred eighty-one".