243390 has 64 divisors (see below), whose sum is σ = 714240. Its totient is φ = 51840.

The previous prime is 243367. The next prime is 243391. The reversal of 243390 is 93342.

243390 = T₁₀₀ + T₁₀₁ + ... + T₁₃₄.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243391) by changing a digit.

243390 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 (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3960 + ... + 4020.

It is an arithmetic number, because the mean of its divisors is an integer number (11160).

2²⁴³³⁹⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 243390, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (357120).

243390 is an abundant number, since it is smaller than the sum of its proper divisors (470850).

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

243390 is a wasteful number, since it uses less digits than its factorization.

243390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97.

The product of its (nonzero) digits is 648, while the sum is 21.

The square root of 243390 is about 493.3457205652. The cubic root of 243390 is about 62.4358809090.

The spelling of 243390 in words is "two hundred forty-three thousand, three hundred ninety".