21765445643 has 2 divisors, whose sum is σ = 21765445644. Its totient is φ = 21765445642.

The previous prime is 21765445591. The next prime is 21765445699. The reversal of 21765445643 is 34654456712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21765445643 - 2²² = 21761251339 is a prime.

It is not a weakly prime, because it can be changed into another prime (21765445043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10882722821 + 10882722822.

It is an arithmetic number, because the mean of its divisors is an integer number (10882722822).

Almost surely, 2^21765445643 is an apocalyptic number.

21765445643 is a deficient number, since it is larger than the sum of its proper divisors (1).

21765445643 is an equidigital number, since it uses as much as digits as its factorization.

21765445643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2419200, while the sum is 47.

The spelling of 21765445643 in words is "twenty-one billion, seven hundred sixty-five million, four hundred forty-five thousand, six hundred forty-three".