81774289 has 2 divisors, whose sum is σ = 81774290. Its totient is φ = 81774288.

The previous prime is 81774281. The next prime is 81774299. The reversal of 81774289 is 98247718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42185025 + 39589264 = 6495^2 + 6292^2 .

It is a cyclic number.

It is not a de Polignac number, because 81774289 - 2³ = 81774281 is a prime.

It is not a weakly prime, because it can be changed into another prime (81774281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40887144 + 40887145.

It is an arithmetic number, because the mean of its divisors is an integer number (40887145).

Almost surely, 2^81774289 is an apocalyptic number.

It is an amenable number.

81774289 is a deficient number, since it is larger than the sum of its proper divisors (1).

81774289 is an equidigital number, since it uses as much as digits as its factorization.

81774289 is an evil number, because the sum of its binary digits is even.

The product of its digits is 225792, while the sum is 46.

The square root of 81774289 is about 9042.9137450271. The cubic root of 81774289 is about 434.0491655033.

The spelling of 81774289 in words is "eighty-one million, seven hundred seventy-four thousand, two hundred eighty-nine".