21427663816643 has 4 divisors (see below), whose sum is σ = 24488758647600. Its totient is φ = 18366568985688.

The previous prime is 21427663816633. The next prime is 21427663816673. The reversal of 21427663816643 is 34661836672412.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21427663816643 - 2¹⁰ = 21427663815619 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21427663816633) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1530547415468 + ... + 1530547415481.

It is an arithmetic number, because the mean of its divisors is an integer number (6122189661900).

Almost surely, 2^{21427663816643} is an apocalyptic number.

21427663816643 is a deficient number, since it is larger than the sum of its proper divisors (3061094830957).

21427663816643 is an equidigital number, since it uses as much as digits as its factorization.

21427663816643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3061094830956.

The product of its digits is 41803776, while the sum is 59.

The spelling of 21427663816643 in words is "twenty-one trillion, four hundred twenty-seven billion, six hundred sixty-three million, eight hundred sixteen thousand, six hundred forty-three".