42390 has 32 divisors (see below), whose sum is σ = 113760. Its totient is φ = 11232.

The previous prime is 42379. The next prime is 42391. The reversal of 42390 is 9324.

42390 is digitally balanced in base 2 and base 6, because in such bases it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an Ulam number.

42390 is strictly pandigital in base 6.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42391) by changing a digit.

42390 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 192 + ... + 348.

It is an arithmetic number, because the mean of its divisors is an integer number (3555).

2⁴²³⁹⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 42390, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (56880).

42390 is an abundant number, since it is smaller than the sum of its proper divisors (71370).

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

42390 is a wasteful number, since it uses less digits than its factorization.

42390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 42390 is about 205.8883192413. Note that the first 3 decimals coincide. The cubic root of 42390 is about 34.8675264365.

The spelling of 42390 in words is "forty-two thousand, three hundred ninety".