20661266473 has 2 divisors, whose sum is σ = 20661266474. Its totient is φ = 20661266472.

The previous prime is 20661266471. The next prime is 20661266513. The reversal of 20661266473 is 37466216602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19144319769 + 1516946704 = 138363^2 + 38948^2 .

It is a cyclic number.

It is not a de Polignac number, because 20661266473 - 2¹ = 20661266471 is a prime.

Together with 20661266471, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20661266471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10330633236 + 10330633237.

It is an arithmetic number, because the mean of its divisors is an integer number (10330633237).

Almost surely, 2^20661266473 is an apocalyptic number.

It is an amenable number.

20661266473 is a deficient number, since it is larger than the sum of its proper divisors (1).

20661266473 is an equidigital number, since it uses as much as digits as its factorization.

20661266473 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 435456, while the sum is 43.

The spelling of 20661266473 in words is "twenty billion, six hundred sixty-one million, two hundred sixty-six thousand, four hundred seventy-three".