638253449 has 2 divisors, whose sum is σ = 638253450. Its totient is φ = 638253448.

The previous prime is 638253439. The next prime is 638253481. The reversal of 638253449 is 944352836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 394737424 + 243516025 = 19868^2 + 15605^2 .

It is a cyclic number.

It is not a de Polignac number, because 638253449 - 2⁴ = 638253433 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (638253419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319126724 + 319126725.

It is an arithmetic number, because the mean of its divisors is an integer number (319126725).

Almost surely, 2^638253449 is an apocalyptic number.

It is an amenable number.

638253449 is a deficient number, since it is larger than the sum of its proper divisors (1).

638253449 is an equidigital number, since it uses as much as digits as its factorization.

638253449 is an evil number, because the sum of its binary digits is even.

The product of its digits is 622080, while the sum is 44.

The square root of 638253449 is about 25263.6784534636. The cubic root of 638253449 is about 860.9892388951.

The spelling of 638253449 in words is "six hundred thirty-eight million, two hundred fifty-three thousand, four hundred forty-nine".