242721 has 12 divisors (see below), whose sum is σ = 354900. Its totient is φ = 159840.

The previous prime is 242713. The next prime is 242729. The reversal of 242721 is 127242.

It is an interprime number because it is at equal distance from previous prime (242713) and next prime (242729).

It can be written as a sum of positive squares in 2 ways, for example, as 12321 + 230400 = 111^2 + 480^2 .

It is not a de Polignac number, because 242721 - 2³ = 242713 is a prime.

242721 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 242694 and 242703.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 242721.

It is not an unprimeable number, because it can be changed into a prime (242729) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1251 + ... + 1431.

It is an arithmetic number, because the mean of its divisors is an integer number (29575).

2²⁴²⁷²¹ is an apocalyptic number.

It is an amenable number.

242721 is a deficient number, since it is larger than the sum of its proper divisors (112179).

242721 is a wasteful number, since it uses less digits than its factorization.

242721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336 (or 333 counting only the distinct ones).

The product of its digits is 224, while the sum is 18.

The square root of 242721 is about 492.6672304913. The cubic root of 242721 is about 62.3786231016.

Adding to 242721 its reverse (127242), we get a palindrome (369963).

The spelling of 242721 in words is "two hundred forty-two thousand, seven hundred twenty-one", and thus it is an iban number.