81494909 has 2 divisors, whose sum is σ = 81494910. Its totient is φ = 81494908.

The previous prime is 81494893. The next prime is 81494927. The reversal of 81494909 is 90949418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77827684 + 3667225 = 8822^2 + 1915^2 .

It is a cyclic number.

It is not a de Polignac number, because 81494909 - 2⁴ = 81494893 is a prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 81494909.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81494929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40747454 + 40747455.

It is an arithmetic number, because the mean of its divisors is an integer number (40747455).

Almost surely, 2^81494909 is an apocalyptic number.

It is an amenable number.

81494909 is a deficient number, since it is larger than the sum of its proper divisors (1).

81494909 is an equidigital number, since it uses as much as digits as its factorization.

81494909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 93312, while the sum is 44.

The square root of 81494909 is about 9027.4530738188. The cubic root of 81494909 is about 433.5542951336.

The spelling of 81494909 in words is "eighty-one million, four hundred ninety-four thousand, nine hundred nine".