21665448043 has 2 divisors, whose sum is σ = 21665448044. Its totient is φ = 21665448042.

The previous prime is 21665448037. The next prime is 21665448059. The reversal of 21665448043 is 34084456612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21665448043 - 2¹⁷ = 21665316971 is a prime.

It is not a weakly prime, because it can be changed into another prime (21665448143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10832724021 + 10832724022.

It is an arithmetic number, because the mean of its divisors is an integer number (10832724022).

Almost surely, 2^21665448043 is an apocalyptic number.

21665448043 is a deficient number, since it is larger than the sum of its proper divisors (1).

21665448043 is an equidigital number, since it uses as much as digits as its factorization.

21665448043 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 552960, while the sum is 43.

The spelling of 21665448043 in words is "twenty-one billion, six hundred sixty-five million, four hundred forty-eight thousand, forty-three".