42138 has 12 divisors (see below), whose sum is σ = 91338. Its totient is φ = 14040.

The previous prime is 42131. The next prime is 42139. The reversal of 42138 is 83124.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 33489 + 8649 = 183^2 + 93^2 .

It is a super-2 number, since 2×42138² = 3551222088, which contains 22 as substring.

It is a Smith number, since the sum of its digits (18) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (18), and also a Moran number because the ratio is a prime number: 2341 = 42138 / (4 + 2 + 1 + 3 + 8).

It is a nialpdrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 42138.

It is not an unprimeable number, because it can be changed into a prime (42131) by changing a digit.

42138 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 5 ways as a sum of consecutive naturals, for example, 1153 + ... + 1188.

2⁴²¹³⁸ is an apocalyptic number.

42138 is an abundant number, since it is smaller than the sum of its proper divisors (49200).

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

42138 is a wasteful number, since it uses less digits than its factorization.

42138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2349 (or 2346 counting only the distinct ones).

The product of its digits is 192, while the sum is 18.

The square root of 42138 is about 205.2754247347. The cubic root of 42138 is about 34.7982955963.

The spelling of 42138 in words is "forty-two thousand, one hundred thirty-eight".