638323657 has 2 divisors, whose sum is σ = 638323658. Its totient is φ = 638323656.

The previous prime is 638323649. The next prime is 638323661. The reversal of 638323657 is 756323836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 483296256 + 155027401 = 21984^2 + 12451^2 .

It is a cyclic number.

It is not a de Polignac number, because 638323657 - 2³ = 638323649 is a prime.

It is not a weakly prime, because it can be changed into another prime (638323687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319161828 + 319161829.

It is an arithmetic number, because the mean of its divisors is an integer number (319161829).

Almost surely, 2^638323657 is an apocalyptic number.

It is an amenable number.

638323657 is a deficient number, since it is larger than the sum of its proper divisors (1).

638323657 is an equidigital number, since it uses as much as digits as its factorization.

638323657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 544320, while the sum is 43.

The square root of 638323657 is about 25265.0679199562. The cubic root of 638323657 is about 861.0208073973.

The spelling of 638323657 in words is "six hundred thirty-eight million, three hundred twenty-three thousand, six hundred fifty-seven".