638073871 has 4 divisors (see below), whose sum is σ = 645761592. Its totient is φ = 630386152.

The previous prime is 638073851. The next prime is 638073881. The reversal of 638073871 is 178370836.

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-638073871 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 (638073851) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3843736 + ... + 3843901.

It is an arithmetic number, because the mean of its divisors is an integer number (161440398).

Almost surely, 2^638073871 is an apocalyptic number.

638073871 is a deficient number, since it is larger than the sum of its proper divisors (7687721).

638073871 is an equidigital number, since it uses as much as digits as its factorization.

638073871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7687720.

The product of its (nonzero) digits is 169344, while the sum is 43.

The square root of 638073871 is about 25260.1241287528. The cubic root of 638073871 is about 860.9084824554.

The spelling of 638073871 in words is "six hundred thirty-eight million, seventy-three thousand, eight hundred seventy-one".