638242836 has 144 divisors (see below), whose sum is σ = 1910526912. Its totient is φ = 163968000.

The previous prime is 638242823. The next prime is 638242867.

638242836 is nontrivially palindromic in base 10.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 652780 + ... + 653756.

It is an arithmetic number, because the mean of its divisors is an integer number (13267548).

Almost surely, 2^638242836 is an apocalyptic number.

638242836 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638242836, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (955263456).

638242836 is an abundant number, since it is smaller than the sum of its proper divisors (1272284076).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638242836 is a wasteful number, since it uses less digits than its factorization.

638242836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1110 (or 1101 counting only the distinct ones).

The product of its digits is 331776, while the sum is 42.

The square root of 638242836 is about 25263.4684079601. The cubic root of 638242836 is about 860.9844666376.

The spelling of 638242836 in words is "six hundred thirty-eight million, two hundred forty-two thousand, eight hundred thirty-six".