138523644 has 72 divisors (see below), whose sum is σ = 402522848. Its totient is φ = 39346560.

The previous prime is 138523643. The next prime is 138523657. The reversal of 138523644 is 446325831.

138523644 is a `hidden beast` number, since 1 + 3 + 8 + 5 + 2 + 3 + 644 = 666.

138523644 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 138523599 and 138523608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138523643) 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, 44094 + ... + 47130.

Almost surely, 2^138523644 is an apocalyptic number.

138523644 is a gapful number since it is divisible by the number (14) 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 138523644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (201261424).

138523644 is an abundant number, since it is smaller than the sum of its proper divisors (263999204).

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

138523644 is a wasteful number, since it uses less digits than its factorization.

138523644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3235 (or 3230 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

The square root of 138523644 is about 11769.6067903732. The cubic root of 138523644 is about 517.4177254906.

It can be divided in two parts, 1385236 and 44, that added together give a triangular number (1385280 = T₁₆₆₄).

The spelling of 138523644 in words is "one hundred thirty-eight million, five hundred twenty-three thousand, six hundred forty-four".