638308247 has 4 divisors (see below), whose sum is σ = 647298576. Its totient is φ = 629317920.

The previous prime is 638308207. The next prime is 638308283. The reversal of 638308247 is 742803836.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638308247 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638308207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4495058 + ... + 4495199.

It is an arithmetic number, because the mean of its divisors is an integer number (161824644).

Almost surely, 2^638308247 is an apocalyptic number.

638308247 is a deficient number, since it is larger than the sum of its proper divisors (8990329).

638308247 is an equidigital number, since it uses as much as digits as its factorization.

638308247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8990328.

The product of its (nonzero) digits is 193536, while the sum is 41.

The square root of 638308247 is about 25264.7629515893. The cubic root of 638308247 is about 861.0138786043.

The spelling of 638308247 in words is "six hundred thirty-eight million, three hundred eight thousand, two hundred forty-seven".