6642037536781 has 2 divisors, whose sum is σ = 6642037536782. Its totient is φ = 6642037536780.

The previous prime is 6642037536737. The next prime is 6642037536809. The reversal of 6642037536781 is 1876357302466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6191467686756 + 450569850025 = 2488266^2 + 671245^2 .

It is a cyclic number.

It is not a de Polignac number, because 6642037536781 - 2⁷ = 6642037536653 is a prime.

It is a super-2 number, since 2×6642037536781² (a number of 26 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6642037536881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3321018768390 + 3321018768391.

It is an arithmetic number, because the mean of its divisors is an integer number (3321018768391).

Almost surely, 2^{6642037536781} is an apocalyptic number.

It is an amenable number.

6642037536781 is a deficient number, since it is larger than the sum of its proper divisors (1).

6642037536781 is an equidigital number, since it uses as much as digits as its factorization.

6642037536781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30481920, while the sum is 58.

The spelling of 6642037536781 in words is "six trillion, six hundred forty-two billion, thirty-seven million, five hundred thirty-six thousand, seven hundred eighty-one".