6665410369721 has 2 divisors, whose sum is σ = 6665410369722. Its totient is φ = 6665410369720.

The previous prime is 6665410369697. The next prime is 6665410369819. The reversal of 6665410369721 is 1279630145666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6665376264121 + 34105600 = 2581739^2 + 5840^2 .

It is a cyclic number.

It is not a de Polignac number, because 6665410369721 - 2³⁴ = 6648230500537 is a prime.

It is not a weakly prime, because it can be changed into another prime (6665410369921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3332705184860 + 3332705184861.

It is an arithmetic number, because the mean of its divisors is an integer number (3332705184861).

Almost surely, 2^{6665410369721} is an apocalyptic number.

It is an amenable number.

6665410369721 is a deficient number, since it is larger than the sum of its proper divisors (1).

6665410369721 is an equidigital number, since it uses as much as digits as its factorization.

6665410369721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9797760, while the sum is 56.

The spelling of 6665410369721 in words is "six trillion, six hundred sixty-five billion, four hundred ten million, three hundred sixty-nine thousand, seven hundred twenty-one".