8638021649 has 2 divisors, whose sum is σ = 8638021650. Its totient is φ = 8638021648.

The previous prime is 8638021633. The next prime is 8638021669. The reversal of 8638021649 is 9461208368.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6549988624 + 2088033025 = 80932^2 + 45695^2 .

It is a cyclic number.

It is not a de Polignac number, because 8638021649 - 2⁴ = 8638021633 is a prime.

It is not a weakly prime, because it can be changed into another prime (8638021619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4319010824 + 4319010825.

It is an arithmetic number, because the mean of its divisors is an integer number (4319010825).

Almost surely, 2^8638021649 is an apocalyptic number.

It is an amenable number.

8638021649 is a deficient number, since it is larger than the sum of its proper divisors (1).

8638021649 is an equidigital number, since it uses as much as digits as its factorization.

8638021649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 497664, while the sum is 47.

The square root of 8638021649 is about 92940.9578657332. The cubic root of 8638021649 is about 2051.8145068055.

The spelling of 8638021649 in words is "eight billion, six hundred thirty-eight million, twenty-one thousand, six hundred forty-nine".