20716287491 has 2 divisors, whose sum is σ = 20716287492. Its totient is φ = 20716287490.

The previous prime is 20716287463. The next prime is 20716287517. The reversal of 20716287491 is 19478261702.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20716287491 - 2¹⁰ = 20716286467 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (20716287191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10358143745 + 10358143746.

It is an arithmetic number, because the mean of its divisors is an integer number (10358143746).

Almost surely, 2^20716287491 is an apocalyptic number.

20716287491 is a deficient number, since it is larger than the sum of its proper divisors (1).

20716287491 is an equidigital number, since it uses as much as digits as its factorization.

20716287491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 338688, while the sum is 47.

The spelling of 20716287491 in words is "twenty billion, seven hundred sixteen million, two hundred eighty-seven thousand, four hundred ninety-one".