138212640 has 144 divisors (see below), whose sum is σ = 483360696. Its totient is φ = 35942400.

The previous prime is 138212617. The next prime is 138212671. The reversal of 138212640 is 46212831.

138212640 is a `hidden beast` number, since 1 + 3 + 8 + 2 + 12 + 640 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 85155984 + 53056656 = 9228^2 + 7284^2 .

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

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, 57870 + ... + 60210.

Almost surely, 2^138212640 is an apocalyptic number.

138212640 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 138212640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (241680348).

138212640 is an abundant number, since it is smaller than the sum of its proper divisors (345148056).

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

138212640 is a wasteful number, since it uses less digits than its factorization.

138212640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2403 (or 2392 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 138212640 is about 11756.3872001563. The cubic root of 138212640 is about 517.0302114744.

It can be divided in two parts, 13821 and 2640, that added together give a palindrome (16461).

The spelling of 138212640 in words is "one hundred thirty-eight million, two hundred twelve thousand, six hundred forty".