638323649 has 2 divisors, whose sum is σ = 638323650. Its totient is φ = 638323648.

The previous prime is 638323619. The next prime is 638323657. The reversal of 638323649 is 946323836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 443860624 + 194463025 = 21068^2 + 13945^2 .

It is a cyclic number.

It is not a de Polignac number, because 638323649 - 2²⁴ = 621546433 is a prime.

It is not a weakly prime, because it can be changed into another prime (638323619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319161824 + 319161825.

It is an arithmetic number, because the mean of its divisors is an integer number (319161825).

Almost surely, 2^638323649 is an apocalyptic number.

It is an amenable number.

638323649 is a deficient number, since it is larger than the sum of its proper divisors (1).

638323649 is an equidigital number, since it uses as much as digits as its factorization.

638323649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 559872, while the sum is 44.

The square root of 638323649 is about 25265.0677616348. The cubic root of 638323649 is about 861.0208038003.

The spelling of 638323649 in words is "six hundred thirty-eight million, three hundred twenty-three thousand, six hundred forty-nine".