1266020605661 has 16 divisors (see below), whose sum is σ = 1535529469824. Its totient is φ = 1018968781824.

The previous prime is 1266020605651. The next prime is 1266020605669. The reversal of 1266020605661 is 1665060206621.

It is not a de Polignac number, because 1266020605661 - 2³⁰ = 1264946863837 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1266020605669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12233495 + ... + 12336548.

It is an arithmetic number, because the mean of its divisors is an integer number (95970591864).

Almost surely, 2^{1266020605661} is an apocalyptic number.

It is an amenable number.

1266020605661 is a deficient number, since it is larger than the sum of its proper divisors (269508864163).

1266020605661 is a wasteful number, since it uses less digits than its factorization.

1266020605661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24570500.

The product of its (nonzero) digits is 155520, while the sum is 41.

The spelling of 1266020605661 in words is "one trillion, two hundred sixty-six billion, twenty million, six hundred five thousand, six hundred sixty-one".