138581856 has 144 divisors (see below), whose sum is σ = 459242784. Its totient is φ = 38817792.

The previous prime is 138581843. The next prime is 138581857. The reversal of 138581856 is 658185831.

138581856 is a `hidden beast` number, since 13 + 8 + 581 + 8 + 56 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138581857) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 106200 + ... + 107496.

It is an arithmetic number, because the mean of its divisors is an integer number (3189186).

Almost surely, 2^138581856 is an apocalyptic number.

138581856 is a gapful number since it is divisible by the number (16) 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 138581856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (229621392).

138581856 is an abundant number, since it is smaller than the sum of its proper divisors (320660928).

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

138581856 is a wasteful number, since it uses less digits than its factorization.

138581856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1373 (or 1362 counting only the distinct ones).

The product of its digits is 230400, while the sum is 45.

The square root of 138581856 is about 11772.0795104348. The cubic root of 138581856 is about 517.4901937510.

It can be divided in two parts, 138 and 581856, that multiplied together give a triangular number (80296128 = T₁₂₆₇₂).

The spelling of 138581856 in words is "one hundred thirty-eight million, five hundred eighty-one thousand, eight hundred fifty-six".