243451981 has 2 divisors, whose sum is σ = 243451982. Its totient is φ = 243451980.

The previous prime is 243451927. The next prime is 243452003. The reversal of 243451981 is 189154342.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 228312100 + 15139881 = 15110^2 + 3891^2 .

It is a cyclic number.

It is not a de Polignac number, because 243451981 - 2⁹ = 243451469 is a prime.

It is a super-2 number, since 2×243451981² = 118537734105648722, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 243451981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243451081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121725990 + 121725991.

It is an arithmetic number, because the mean of its divisors is an integer number (121725991).

Almost surely, 2^243451981 is an apocalyptic number.

It is an amenable number.

243451981 is a deficient number, since it is larger than the sum of its proper divisors (1).

243451981 is an equidigital number, since it uses as much as digits as its factorization.

243451981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34560, while the sum is 37.

The square root of 243451981 is about 15602.9478304582. The cubic root of 243451981 is about 624.4118037339.

The spelling of 243451981 in words is "two hundred forty-three million, four hundred fifty-one thousand, nine hundred eighty-one".