8683991621 has 2 divisors, whose sum is σ = 8683991622. Its totient is φ = 8683991620.

The previous prime is 8683991581. The next prime is 8683991671. The reversal of 8683991621 is 1261993868.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7324963396 + 1359028225 = 85586^2 + 36865^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8683991621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8683991671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4341995810 + 4341995811.

It is an arithmetic number, because the mean of its divisors is an integer number (4341995811).

Almost surely, 2^8683991621 is an apocalyptic number.

It is an amenable number.

8683991621 is a deficient number, since it is larger than the sum of its proper divisors (1).

8683991621 is an equidigital number, since it uses as much as digits as its factorization.

8683991621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1119744, while the sum is 53.

The square root of 8683991621 is about 93187.9371002492. The cubic root of 8683991621 is about 2055.4478629519.

The spelling of 8683991621 in words is "eight billion, six hundred eighty-three million, nine hundred ninety-one thousand, six hundred twenty-one".