1638071849 has 2 divisors, whose sum is σ = 1638071850. Its totient is φ = 1638071848.

The previous prime is 1638071821. The next prime is 1638071861. The reversal of 1638071849 is 9481708361.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1345422400 + 292649449 = 36680^2 + 17107^2 .

It is a cyclic number.

It is not a de Polignac number, because 1638071849 - 2¹⁶ = 1638006313 is a prime.

It is not a weakly prime, because it can be changed into another prime (1638071819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 819035924 + 819035925.

It is an arithmetic number, because the mean of its divisors is an integer number (819035925).

Almost surely, 2^1638071849 is an apocalyptic number.

It is an amenable number.

1638071849 is a deficient number, since it is larger than the sum of its proper divisors (1).

1638071849 is an equidigital number, since it uses as much as digits as its factorization.

1638071849 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 290304, while the sum is 47.

The square root of 1638071849 is about 40473.1003136651. The cubic root of 1638071849 is about 1178.8113686704.

The spelling of 1638071849 in words is "one billion, six hundred thirty-eight million, seventy-one thousand, eight hundred forty-nine".