6661220356513 has 2 divisors, whose sum is σ = 6661220356514. Its totient is φ = 6661220356512.

The previous prime is 6661220356499. The next prime is 6661220356529. The reversal of 6661220356513 is 3156530221666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6648909788304 + 12310568209 = 2578548^2 + 110953^2 .

It is a cyclic number.

It is not a de Polignac number, because 6661220356513 - 2⁹ = 6661220356001 is a prime.

It is not a weakly prime, because it can be changed into another prime (6661220356543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3330610178256 + 3330610178257.

It is an arithmetic number, because the mean of its divisors is an integer number (3330610178257).

Almost surely, 2^{6661220356513} is an apocalyptic number.

It is an amenable number.

6661220356513 is a deficient number, since it is larger than the sum of its proper divisors (1).

6661220356513 is an equidigital number, since it uses as much as digits as its factorization.

6661220356513 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1166400, while the sum is 46.

The spelling of 6661220356513 in words is "six trillion, six hundred sixty-one billion, two hundred twenty million, three hundred fifty-six thousand, five hundred thirteen".