8641729021 has 2 divisors, whose sum is σ = 8641729022. Its totient is φ = 8641729020.

The previous prime is 8641729009. The next prime is 8641729069. The reversal of 8641729021 is 1209271468.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8229029796 + 412699225 = 90714^2 + 20315^2 .

It is a cyclic number.

It is not a de Polignac number, because 8641729021 - 2⁹ = 8641728509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8641729091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4320864510 + 4320864511.

It is an arithmetic number, because the mean of its divisors is an integer number (4320864511).

Almost surely, 2^8641729021 is an apocalyptic number.

It is an amenable number.

8641729021 is a deficient number, since it is larger than the sum of its proper divisors (1).

8641729021 is an equidigital number, since it uses as much as digits as its factorization.

8641729021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48384, while the sum is 40.

The square root of 8641729021 is about 92960.9004958536. The cubic root of 8641729021 is about 2052.1080057862.

The spelling of 8641729021 in words is "eight billion, six hundred forty-one million, seven hundred twenty-nine thousand, twenty-one".