8381683721 has 2 divisors, whose sum is σ = 8381683722. Its totient is φ = 8381683720.

The previous prime is 8381683699. The next prime is 8381683727. The reversal of 8381683721 is 1273861838.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7551610000 + 830073721 = 86900^2 + 28811^2 .

It is a cyclic number.

It is not a de Polignac number, because 8381683721 - 2⁶ = 8381683657 is a prime.

It is not a weakly prime, because it can be changed into another prime (8381683727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4190841860 + 4190841861.

It is an arithmetic number, because the mean of its divisors is an integer number (4190841861).

Almost surely, 2^8381683721 is an apocalyptic number.

It is an amenable number.

8381683721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8381683721 is an equidigital number, since it uses as much as digits as its factorization.

8381683721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 387072, while the sum is 47.

The square root of 8381683721 is about 91551.5358746100. The cubic root of 8381683721 is about 2031.3141305436.

The spelling of 8381683721 in words is "eight billion, three hundred eighty-one million, six hundred eighty-three thousand, seven hundred twenty-one".