20501311643 has 2 divisors, whose sum is σ = 20501311644. Its totient is φ = 20501311642.

The previous prime is 20501311613. The next prime is 20501311667. The reversal of 20501311643 is 34611310502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20501311643 - 2²⁶ = 20434202779 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (20501311613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10250655821 + 10250655822.

It is an arithmetic number, because the mean of its divisors is an integer number (10250655822).

Almost surely, 2^20501311643 is an apocalyptic number.

20501311643 is a deficient number, since it is larger than the sum of its proper divisors (1).

20501311643 is an equidigital number, since it uses as much as digits as its factorization.

20501311643 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 26.

The spelling of 20501311643 in words is "twenty billion, five hundred one million, three hundred eleven thousand, six hundred forty-three".