138678020 has 72 divisors (see below), whose sum is σ = 319583880. Its totient is φ = 50519040.

The previous prime is 138678013. The next prime is 138678047. The reversal of 138678020 is 20876831.

It can be written as a sum of positive squares in 12 ways, for example, as 111471364 + 27206656 = 10558^2 + 5216^2 .

It is a super-2 number, since 2×138678020² = 38463186462240800, which contains 22 as substring.

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, 300590 + ... + 301050.

It is an arithmetic number, because the mean of its divisors is an integer number (4438665).

Almost surely, 2^138678020 is an apocalyptic number.

138678020 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 138678020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (159791940).

138678020 is an abundant number, since it is smaller than the sum of its proper divisors (180905860).

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

138678020 is a wasteful number, since it uses less digits than its factorization.

138678020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 585 (or 570 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 138678020 is about 11776.1632121842. The cubic root of 138678020 is about 517.6098641086.

The spelling of 138678020 in words is "one hundred thirty-eight million, six hundred seventy-eight thousand, twenty".