6511166640421 has 2 divisors, whose sum is σ = 6511166640422. Its totient is φ = 6511166640420.

The previous prime is 6511166640337. The next prime is 6511166640437. The reversal of 6511166640421 is 1240466611156.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3918760731396 + 2592405909025 = 1979586^2 + 1610095^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6511166640421 is a prime.

It is a super-2 number, since 2×6511166640421² (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 (6511166340421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3255583320210 + 3255583320211.

It is an arithmetic number, because the mean of its divisors is an integer number (3255583320211).

Almost surely, 2^{6511166640421} is an apocalyptic number.

It is an amenable number.

6511166640421 is a deficient number, since it is larger than the sum of its proper divisors (1).

6511166640421 is an equidigital number, since it uses as much as digits as its factorization.

6511166640421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 207360, while the sum is 43.

The spelling of 6511166640421 in words is "six trillion, five hundred eleven billion, one hundred sixty-six million, six hundred forty thousand, four hundred twenty-one".