138611808 has 72 divisors (see below), whose sum is σ = 396219096. Its totient is φ = 45964800.

The previous prime is 138611797. The next prime is 138611843. The reversal of 138611808 is 808116831.

138611808 is a `hidden beast` number, since 1 + 38 + 611 + 8 + 0 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

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 11 ways as a sum of consecutive naturals, for example, 59628 + ... + 61908.

It is an arithmetic number, because the mean of its divisors is an integer number (5503043).

Almost surely, 2^138611808 is an apocalyptic number.

138611808 is a gapful number since it is divisible by the number (18) 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 138611808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (198109548).

138611808 is an abundant number, since it is smaller than the sum of its proper divisors (257607288).

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

138611808 is a wasteful number, since it uses less digits than its factorization.

138611808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2508 (or 2497 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 36.

The square root of 138611808 is about 11773.3516043648. The cubic root of 138611808 is about 517.5274731617.

The spelling of 138611808 in words is "one hundred thirty-eight million, six hundred eleven thousand, eight hundred eight".