21305869643 has 2 divisors, whose sum is σ = 21305869644. Its totient is φ = 21305869642.

The previous prime is 21305869619. The next prime is 21305869679. The reversal of 21305869643 is 34696850312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21305869643 - 2⁶ = 21305869579 is a prime.

It is not a weakly prime, because it can be changed into another prime (21305860643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10652934821 + 10652934822.

It is an arithmetic number, because the mean of its divisors is an integer number (10652934822).

Almost surely, 2^21305869643 is an apocalyptic number.

21305869643 is a deficient number, since it is larger than the sum of its proper divisors (1).

21305869643 is an equidigital number, since it uses as much as digits as its factorization.

21305869643 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 933120, while the sum is 47.

The spelling of 21305869643 in words is "twenty-one billion, three hundred five million, eight hundred sixty-nine thousand, six hundred forty-three".