138820 has 24 divisors (see below), whose sum is σ = 318528. Its totient is φ = 50400.

The previous prime is 138799. The next prime is 138821. The reversal of 138820 is 28831.

138820 = T₂₉ + T₃₀ + ... + T₉₄.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a nialpdrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 138791 and 138800.

It is not an unprimeable number, because it can be changed into a prime (138821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 96 + ... + 535.

It is an arithmetic number, because the mean of its divisors is an integer number (13272).

2¹³⁸⁸²⁰ is an apocalyptic number.

138820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

138820 is an abundant number, since it is smaller than the sum of its proper divisors (179708).

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

138820 is a wasteful number, since it uses less digits than its factorization.

138820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 651 (or 649 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 22.

The square root of 138820 is about 372.5855606435. The cubic root of 138820 is about 51.7786448648.

The spelling of 138820 in words is "one hundred thirty-eight thousand, eight hundred twenty".