20661266478 has 16 divisors (see below), whose sum is σ = 41561393616. Its totient is φ = 6847278720.

The previous prime is 20661266473. The next prime is 20661266513. The reversal of 20661266478 is 87466216602.

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 7 ways as a sum of consecutive naturals, for example, 9951403 + ... + 9953478.

It is an arithmetic number, because the mean of its divisors is an integer number (2597587101).

Almost surely, 2^20661266478 is an apocalyptic number.

20661266478 is an abundant number, since it is smaller than the sum of its proper divisors (20900127138).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20661266478 is a wasteful number, since it uses less digits than its factorization.

20661266478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19905059.

The product of its (nonzero) digits is 1161216, while the sum is 48.

The spelling of 20661266478 in words is "twenty billion, six hundred sixty-one million, two hundred sixty-six thousand, four hundred seventy-eight".