638861390 has 8 divisors (see below), whose sum is σ = 1149950520. Its totient is φ = 255544552.

The previous prime is 638861383. The next prime is 638861393. The reversal of 638861390 is 93168836.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638861393) 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, 31943060 + ... + 31943079.

It is an arithmetic number, because the mean of its divisors is an integer number (143743815).

Almost surely, 2^638861390 is an apocalyptic number.

638861390 is a deficient number, since it is larger than the sum of its proper divisors (511089130).

638861390 is a wasteful number, since it uses less digits than its factorization.

638861390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63886146.

The product of its (nonzero) digits is 186624, while the sum is 44.

The square root of 638861390 is about 25275.7075074072. The cubic root of 638861390 is about 861.2625182938.

The spelling of 638861390 in words is "six hundred thirty-eight million, eight hundred sixty-one thousand, three hundred ninety".