138537216 has 216 divisors, whose sum is σ = 441945504. Its totient is φ = 43130880.

The previous prime is 138537197. The next prime is 138537221. The reversal of 138537216 is 612735831.

It is a tau number, because it is divible by the number of its divisors (216).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1057471 + ... + 1057601.

It is an arithmetic number, because the mean of its divisors is an integer number (2046044).

Almost surely, 2^138537216 is an apocalyptic number.

138537216 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 138537216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (220972752).

138537216 is an abundant number, since it is smaller than the sum of its proper divisors (303408288).

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

138537216 is an equidigital number, since it uses as much as digits as its factorization.

138537216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179 (or 153 counting only the distinct ones).

The product of its digits is 30240, while the sum is 36.

The square root of 138537216 is about 11770.1833460656. The cubic root of 138537216 is about 517.4346231211.

The spelling of 138537216 in words is "one hundred thirty-eight million, five hundred thirty-seven thousand, two hundred sixteen".