6445528781 has 2 divisors, whose sum is σ = 6445528782. Its totient is φ = 6445528780.

The previous prime is 6445528753. The next prime is 6445528787. The reversal of 6445528781 is 1878255446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5999896681 + 445632100 = 77459^2 + 21110^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6445528781 is a prime.

It is a super-3 number, since 3×6445528781³ (a number of 30 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6445528787) 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, 3222764390 + 3222764391.

It is an arithmetic number, because the mean of its divisors is an integer number (3222764391).

Almost surely, 2^6445528781 is an apocalyptic number.

It is an amenable number.

6445528781 is a deficient number, since it is larger than the sum of its proper divisors (1).

6445528781 is an equidigital number, since it uses as much as digits as its factorization.

6445528781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2150400, while the sum is 50.

The square root of 6445528781 is about 80284.0506015983. The cubic root of 6445528781 is about 1861.0277571439.

The spelling of 6445528781 in words is "six billion, four hundred forty-five million, five hundred twenty-eight thousand, seven hundred eighty-one".