243490781 has 2 divisors, whose sum is σ = 243490782. Its totient is φ = 243490780.

The previous prime is 243490729. The next prime is 243490783. The reversal of 243490781 is 187094342.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 240715225 + 2775556 = 15515^2 + 1666^2 .

It is a cyclic number.

It is not a de Polignac number, because 243490781 - 2¹⁴ = 243474397 is a prime.

It is a super-2 number, since 2×243490781² = 118575520863979922, which contains 22 as substring.

Together with 243490783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243490783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121745390 + 121745391.

It is an arithmetic number, because the mean of its divisors is an integer number (121745391).

Almost surely, 2^243490781 is an apocalyptic number.

It is an amenable number.

243490781 is a deficient number, since it is larger than the sum of its proper divisors (1).

243490781 is an equidigital number, since it uses as much as digits as its factorization.

243490781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48384, while the sum is 38.

The square root of 243490781 is about 15604.1911357174. The cubic root of 243490781 is about 624.4449737125. Note that the first 3 decimals are identical.

The spelling of 243490781 in words is "two hundred forty-three million, four hundred ninety thousand, seven hundred eighty-one".