1565100166661 has 2 divisors, whose sum is σ = 1565100166662. Its totient is φ = 1565100166660.

The previous prime is 1565100166633. The next prime is 1565100166667. The reversal of 1565100166661 is 1666610015651.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1457558802436 + 107541364225 = 1207294^2 + 327935^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1565100166661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1565100166667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 782550083330 + 782550083331.

It is an arithmetic number, because the mean of its divisors is an integer number (782550083331).

Almost surely, 2^{1565100166661} is an apocalyptic number.

It is an amenable number.

1565100166661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1565100166661 is an equidigital number, since it uses as much as digits as its factorization.

1565100166661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 194400, while the sum is 44.

The spelling of 1565100166661 in words is "one trillion, five hundred sixty-five billion, one hundred million, one hundred sixty-six thousand, six hundred sixty-one".