243142221 has 16 divisors (see below), whose sum is σ = 390003200. Its totient is φ = 131625648.

The previous prime is 243142201. The next prime is 243142243. The reversal of 243142221 is 122241342.

It is not a de Polignac number, because 243142221 - 2⁵ = 243142189 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243142201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 304291 + ... + 305088.

It is an arithmetic number, because the mean of its divisors is an integer number (24375200).

Almost surely, 2^243142221 is an apocalyptic number.

243142221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

243142221 is a deficient number, since it is larger than the sum of its proper divisors (146860979).

243142221 is a wasteful number, since it uses less digits than its factorization.

243142221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 609408.

The product of its digits is 768, while the sum is 21.

The square root of 243142221 is about 15593.0183415527. The cubic root of 243142221 is about 624.1468645724.

Adding to 243142221 its reverse (122241342), we get a palindrome (365383563).

The spelling of 243142221 in words is "two hundred forty-three million, one hundred forty-two thousand, two hundred twenty-one".