138018640 has 20 divisors (see below), whose sum is σ = 320893524. Its totient is φ = 55207424.

The previous prime is 138018637. The next prime is 138018659. The reversal of 138018640 is 46810831.

It can be written as a sum of positive squares in 2 ways, for example, as 49056016 + 88962624 = 7004^2 + 9432^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 862537 + ... + 862696.

Almost surely, 2^138018640 is an apocalyptic number.

138018640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

138018640 is an abundant number, since it is smaller than the sum of its proper divisors (182874884).

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

138018640 is a wasteful number, since it uses less digits than its factorization.

138018640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1725246 (or 1725240 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 31.

The square root of 138018640 is about 11748.1334687686. The cubic root of 138018640 is about 516.7881910927.

The spelling of 138018640 in words is "one hundred thirty-eight million, eighteen thousand, six hundred forty".