81258309 has 20 divisors (see below), whose sum is σ = 132422400. Its totient is φ = 49246920.

The previous prime is 81258299. The next prime is 81258311. The reversal of 81258309 is 90385218.

It is not a de Polignac number, because 81258309 - 2⁵ = 81258277 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81258349) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 44709 + ... + 46490.

It is an arithmetic number, because the mean of its divisors is an integer number (6621120).

Almost surely, 2^81258309 is an apocalyptic number.

It is an amenable number.

81258309 is a deficient number, since it is larger than the sum of its proper divisors (51164091).

81258309 is a wasteful number, since it uses less digits than its factorization.

81258309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91222 (or 91213 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 81258309 is about 9014.3390772702. The cubic root of 81258309 is about 433.1343164353.

The spelling of 81258309 in words is "eighty-one million, two hundred fifty-eight thousand, three hundred nine".