243721123 has 2 divisors, whose sum is σ = 243721124. Its totient is φ = 243721122.

The previous prime is 243721103. The next prime is 243721139. The reversal of 243721123 is 321127342.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 243721123 - 2²¹ = 241623971 is a prime.

It is a super-2 number, since 2×243721123² = 118799971592762258, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (243721103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121860561 + 121860562.

It is an arithmetic number, because the mean of its divisors is an integer number (121860562).

Almost surely, 2^243721123 is an apocalyptic number.

243721123 is a deficient number, since it is larger than the sum of its proper divisors (1).

243721123 is an equidigital number, since it uses as much as digits as its factorization.

243721123 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 25.

The square root of 243721123 is about 15611.5701644646. The cubic root of 243721123 is about 624.6418197302.

Adding to 243721123 its reverse (321127342), we get a palindrome (564848465).

The spelling of 243721123 in words is "two hundred forty-three million, seven hundred twenty-one thousand, one hundred twenty-three".