20661266477 has 6 divisors (see below), whose sum is σ = 21349259694. Its totient is φ = 19994773080.

The previous prime is 20661266473. The next prime is 20661266513. The reversal of 20661266477 is 77466216602.

It can be written as a sum of positive squares in only one way, i.e., 13398988516 + 7262277961 = 115754^2 + 85219^2 .

It is not a de Polignac number, because 20661266477 - 2² = 20661266473 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661266471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 10748918 + ... + 10750839.

It is an arithmetic number, because the mean of its divisors is an integer number (3558209949).

Almost surely, 2^20661266477 is an apocalyptic number.

It is an amenable number.

20661266477 is a deficient number, since it is larger than the sum of its proper divisors (687993217).

20661266477 is an equidigital number, since it uses as much as digits as its factorization.

20661266477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21499819 (or 21499788 counting only the distinct ones).

The product of its (nonzero) digits is 1016064, while the sum is 47.

The spelling of 20661266477 in words is "twenty billion, six hundred sixty-one million, two hundred sixty-six thousand, four hundred seventy-seven".