638872049 has 2 divisors, whose sum is σ = 638872050. Its totient is φ = 638872048.

The previous prime is 638872021. The next prime is 638872051. The reversal of 638872049 is 940278836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 336355600 + 302516449 = 18340^2 + 17393^2 .

It is a cyclic number.

It is not a de Polignac number, because 638872049 - 2¹² = 638867953 is a prime.

It is a Sophie Germain prime.

Together with 638872051, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 638871994 and 638872012.

It is not a weakly prime, because it can be changed into another prime (638872099) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319436024 + 319436025.

It is an arithmetic number, because the mean of its divisors is an integer number (319436025).

Almost surely, 2^638872049 is an apocalyptic number.

It is an amenable number.

638872049 is a deficient number, since it is larger than the sum of its proper divisors (1).

638872049 is an equidigital number, since it uses as much as digits as its factorization.

638872049 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 580608, while the sum is 47.

The square root of 638872049 is about 25275.9183611595. The cubic root of 638872049 is about 861.2673081414.

The spelling of 638872049 in words is "six hundred thirty-eight million, eight hundred seventy-two thousand, forty-nine".