21708791567 has 2 divisors, whose sum is σ = 21708791568. Its totient is φ = 21708791566.

The previous prime is 21708791549. The next prime is 21708791593. The reversal of 21708791567 is 76519780712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21708791567 - 2²⁸ = 21440356111 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21708793567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10854395783 + 10854395784.

It is an arithmetic number, because the mean of its divisors is an integer number (10854395784).

Almost surely, 2^21708791567 is an apocalyptic number.

21708791567 is a deficient number, since it is larger than the sum of its proper divisors (1).

21708791567 is an equidigital number, since it uses as much as digits as its factorization.

21708791567 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1481760, while the sum is 53.

The spelling of 21708791567 in words is "twenty-one billion, seven hundred eight million, seven hundred ninety-one thousand, five hundred sixty-seven".