81954289 has 2 divisors, whose sum is σ = 81954290. Its totient is φ = 81954288.

The previous prime is 81954287. The next prime is 81954311. The reversal of 81954289 is 98245918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 53949025 + 28005264 = 7345^2 + 5292^2 .

It is a cyclic number.

It is not a de Polignac number, because 81954289 - 2¹ = 81954287 is a prime.

Together with 81954287, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (81954287) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40977144 + 40977145.

It is an arithmetic number, because the mean of its divisors is an integer number (40977145).

Almost surely, 2^81954289 is an apocalyptic number.

It is an amenable number.

81954289 is a deficient number, since it is larger than the sum of its proper divisors (1).

81954289 is an equidigital number, since it uses as much as digits as its factorization.

81954289 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 207360, while the sum is 46.

The square root of 81954289 is about 9052.8608185479. The cubic root of 81954289 is about 434.3674056882.

The spelling of 81954289 in words is "eighty-one million, nine hundred fifty-four thousand, two hundred eighty-nine".