20981321567 has 2 divisors, whose sum is σ = 20981321568. Its totient is φ = 20981321566.

The previous prime is 20981321527. The next prime is 20981321677. The reversal of 20981321567 is 76512318902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20981321567 - 2¹⁰ = 20981320543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20981321527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10490660783 + 10490660784.

It is an arithmetic number, because the mean of its divisors is an integer number (10490660784).

Almost surely, 2^20981321567 is an apocalyptic number.

20981321567 is a deficient number, since it is larger than the sum of its proper divisors (1).

20981321567 is an equidigital number, since it uses as much as digits as its factorization.

20981321567 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 181440, while the sum is 44.

The spelling of 20981321567 in words is "twenty billion, nine hundred eighty-one million, three hundred twenty-one thousand, five hundred sixty-seven".