243820 has 24 divisors (see below), whose sum is σ = 522144. Its totient is φ = 95616.

The previous prime is 243809. The next prime is 243829. The reversal of 243820 is 28342.

It is a happy number.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (243829) by changing a digit.

243820 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 7 ways as a sum of consecutive naturals, for example, 1377 + ... + 1543.

It is an arithmetic number, because the mean of its divisors is an integer number (21756).

2²⁴³⁸²⁰ is an apocalyptic number.

243820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

243820 is an abundant number, since it is smaller than the sum of its proper divisors (278324).

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

243820 is a wasteful number, since it uses less digits than its factorization.

243820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249 (or 247 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 243820 is about 493.7813281200. The cubic root of 243820 is about 62.4726280141.

It can be divided in two parts, 24 and 3820, that added together give a square (3844 = 62²).

The spelling of 243820 in words is "two hundred forty-three thousand, eight hundred twenty".