138536640 has 168 divisors, whose sum is σ = 519946128. Its totient is φ = 33576960.

The previous prime is 138536633. The next prime is 138536641. The reversal of 138536640 is 46635831.

138536640 is a `hidden beast` number, since 1 + 3 + 8 + 5 + 3 + 6 + 640 = 666.

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 = 138536595 and 138536604.

It is not an unprimeable number, because it can be changed into a prime (138536641) 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, 29494 + ... + 33866.

Almost surely, 2^138536640 is an apocalyptic number.

138536640 is a gapful number since it is divisible by the number (10) 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 138536640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (259973064).

138536640 is an abundant number, since it is smaller than the sum of its proper divisors (381409488).

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

138536640 is a wasteful number, since it uses less digits than its factorization.

138536640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4407 (or 4394 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 138536640 is about 11770.1588774324. The cubic root of 138536640 is about 517.4339060027.

It can be divided in two parts, 1385 and 36640, that added together give a square (38025 = 195²).

The spelling of 138536640 in words is "one hundred thirty-eight million, five hundred thirty-six thousand, six hundred forty".