20646426481 has 2 divisors, whose sum is σ = 20646426482. Its totient is φ = 20646426480.

The previous prime is 20646426439. The next prime is 20646426487. The reversal of 20646426481 is 18462464602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13780646881 + 6865779600 = 117391^2 + 82860^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20646426481 is a prime.

It is a super-2 number, since 2×20646426481² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20646426487) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10323213240 + 10323213241.

It is an arithmetic number, because the mean of its divisors is an integer number (10323213241).

Almost surely, 2^20646426481 is an apocalyptic number.

It is an amenable number.

20646426481 is a deficient number, since it is larger than the sum of its proper divisors (1).

20646426481 is an equidigital number, since it uses as much as digits as its factorization.

20646426481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 442368, while the sum is 43.

The spelling of 20646426481 in words is "twenty billion, six hundred forty-six million, four hundred twenty-six thousand, four hundred eighty-one".