20646135409 has 2 divisors, whose sum is σ = 20646135410. Its totient is φ = 20646135408.

The previous prime is 20646135373. The next prime is 20646135487. The reversal of 20646135409 is 90453164602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18055834384 + 2590301025 = 134372^2 + 50895^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20646135409 is a prime.

It is not a weakly prime, because it can be changed into another prime (20646136409) 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 as a sum of consecutive naturals, namely, 10323067704 + 10323067705.

It is an arithmetic number, because the mean of its divisors is an integer number (10323067705).

Almost surely, 2^20646135409 is an apocalyptic number.

It is an amenable number.

20646135409 is a deficient number, since it is larger than the sum of its proper divisors (1).

20646135409 is an equidigital number, since it uses as much as digits as its factorization.

20646135409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 155520, while the sum is 40.

The spelling of 20646135409 in words is "twenty billion, six hundred forty-six million, one hundred thirty-five thousand, four hundred nine".