81558949 has 2 divisors, whose sum is σ = 81558950. Its totient is φ = 81558948.

The previous prime is 81558929. The next prime is 81558973. The reversal of 81558949 is 94985518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43797924 + 37761025 = 6618^2 + 6145^2 .

It is a cyclic number.

It is not a de Polignac number, because 81558949 - 2¹⁷ = 81427877 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81558929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40779474 + 40779475.

It is an arithmetic number, because the mean of its divisors is an integer number (40779475).

Almost surely, 2^81558949 is an apocalyptic number.

It is an amenable number.

81558949 is a deficient number, since it is larger than the sum of its proper divisors (1).

81558949 is an equidigital number, since it uses as much as digits as its factorization.

81558949 is an evil number, because the sum of its binary digits is even.

The product of its digits is 518400, while the sum is 49.

The square root of 81558949 is about 9030.9993356217. Note that the first 3 decimals coincide. The cubic root of 81558949 is about 433.6678300276.

The spelling of 81558949 in words is "eighty-one million, five hundred fifty-eight thousand, nine hundred forty-nine".