1666661020511 has 2 divisors, whose sum is σ = 1666661020512. Its totient is φ = 1666661020510.

The previous prime is 1666661020457. The next prime is 1666661020543. The reversal of 1666661020511 is 1150201666661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1666661020511 - 2²² = 1666656826207 is a prime.

It is a super-2 number, since 2×1666661020511² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666661020411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833330510255 + 833330510256.

It is an arithmetic number, because the mean of its divisors is an integer number (833330510256).

Almost surely, 2^{1666661020511} is an apocalyptic number.

1666661020511 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666661020511 is an equidigital number, since it uses as much as digits as its factorization.

1666661020511 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 77760, while the sum is 41.

The spelling of 1666661020511 in words is "one trillion, six hundred sixty-six billion, six hundred sixty-one million, twenty thousand, five hundred eleven".