242987821 has 2 divisors, whose sum is σ = 242987822. Its totient is φ = 242987820.

The previous prime is 242987819. The next prime is 242987861. The reversal of 242987821 is 128789242.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 173448900 + 69538921 = 13170^2 + 8339^2 .

It is a cyclic number.

It is not a de Polignac number, because 242987821 - 2¹ = 242987819 is a prime.

Together with 242987819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (242987861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121493910 + 121493911.

It is an arithmetic number, because the mean of its divisors is an integer number (121493911).

Almost surely, 2^242987821 is an apocalyptic number.

It is an amenable number.

242987821 is a deficient number, since it is larger than the sum of its proper divisors (1).

242987821 is an equidigital number, since it uses as much as digits as its factorization.

242987821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 129024, while the sum is 43.

The square root of 242987821 is about 15588.0666216180. The cubic root of 242987821 is about 624.0147214982.

The spelling of 242987821 in words is "two hundred forty-two million, nine hundred eighty-seven thousand, eight hundred twenty-one".