638889733 has 8 divisors (see below), whose sum is σ = 677986200. Its totient is φ = 599961600.

The previous prime is 638889679. The next prime is 638889787. The reversal of 638889733 is 337988836.

It is an interprime number because it is at equal distance from previous prime (638889679) and next prime (638889787).

It can be written as a sum of positive squares in 4 ways, for example, as 33385284 + 605504449 = 5778^2 + 24607^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638889733 is a prime.

It is a super-2 number, since 2×638889733² = 816360181865622578, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638889233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34218 + ... + 49483.

It is an arithmetic number, because the mean of its divisors is an integer number (84748275).

Almost surely, 2^638889733 is an apocalyptic number.

It is an amenable number.

638889733 is a deficient number, since it is larger than the sum of its proper divisors (39096467).

638889733 is a wasteful number, since it uses less digits than its factorization.

638889733 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84167.

The product of its digits is 5225472, while the sum is 55.

The square root of 638889733 is about 25276.2681778778. The cubic root of 638889733 is about 861.2752547042.

The spelling of 638889733 in words is "six hundred thirty-eight million, eight hundred eighty-nine thousand, seven hundred thirty-three".