21643721159 has 2 divisors, whose sum is σ = 21643721160. Its totient is φ = 21643721158.

The previous prime is 21643721147. The next prime is 21643721213. The reversal of 21643721159 is 95112734612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21643721159 - 2¹⁶ = 21643655623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21643751159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10821860579 + 10821860580.

It is an arithmetic number, because the mean of its divisors is an integer number (10821860580).

Almost surely, 2^21643721159 is an apocalyptic number.

21643721159 is a deficient number, since it is larger than the sum of its proper divisors (1).

21643721159 is an equidigital number, since it uses as much as digits as its factorization.

21643721159 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 41.

The spelling of 21643721159 in words is "twenty-one billion, six hundred forty-three million, seven hundred twenty-one thousand, one hundred fifty-nine".