8391644321 has 2 divisors, whose sum is σ = 8391644322. Its totient is φ = 8391644320.

The previous prime is 8391644249. The next prime is 8391644347. The reversal of 8391644321 is 1234461938.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7645753600 + 745890721 = 87440^2 + 27311^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8391644321 is a prime.

It is not a weakly prime, because it can be changed into another prime (8391644351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4195822160 + 4195822161.

It is an arithmetic number, because the mean of its divisors is an integer number (4195822161).

Almost surely, 2^8391644321 is an apocalyptic number.

It is an amenable number.

8391644321 is a deficient number, since it is larger than the sum of its proper divisors (1).

8391644321 is an equidigital number, since it uses as much as digits as its factorization.

8391644321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 124416, while the sum is 41.

The square root of 8391644321 is about 91605.9185915408. The cubic root of 8391644321 is about 2032.1184676608.

The spelling of 8391644321 in words is "eight billion, three hundred ninety-one million, six hundred forty-four thousand, three hundred twenty-one".