81658949 has 2 divisors, whose sum is σ = 81658950. Its totient is φ = 81658948.

The previous prime is 81658909. The next prime is 81658999. The reversal of 81658949 is 94985618.

It is a happy number.

It is an a-pointer prime, because the next prime (81658999) can be obtained adding 81658949 to its sum of digits (50).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81126049 + 532900 = 9007^2 + 730^2 .

It is a cyclic number.

It is not a de Polignac number, because 81658949 - 2²⁰ = 80610373 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

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

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 81658897 and 81658906.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81658909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40829474 + 40829475.

It is an arithmetic number, because the mean of its divisors is an integer number (40829475).

Almost surely, 2^81658949 is an apocalyptic number.

It is an amenable number.

81658949 is a deficient number, since it is larger than the sum of its proper divisors (1).

81658949 is an equidigital number, since it uses as much as digits as its factorization.

81658949 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 622080, while the sum is 50.

The square root of 81658949 is about 9036.5341254266. The cubic root of 81658949 is about 433.8449986951.

The spelling of 81658949 in words is "eighty-one million, six hundred fifty-eight thousand, nine hundred forty-nine".