81558371 has 2 divisors, whose sum is σ = 81558372. Its totient is φ = 81558370.

The previous prime is 81558349. The next prime is 81558413. The reversal of 81558371 is 17385518.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81558371 is a prime.

It is not a weakly prime, because it can be changed into another prime (81558311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40779185 + 40779186.

It is an arithmetic number, because the mean of its divisors is an integer number (40779186).

Almost surely, 2^81558371 is an apocalyptic number.

81558371 is a deficient number, since it is larger than the sum of its proper divisors (1).

81558371 is an equidigital number, since it uses as much as digits as its factorization.

81558371 is an evil number, because the sum of its binary digits is even.

The product of its digits is 33600, while the sum is 38.

The square root of 81558371 is about 9030.9673346768. The cubic root of 81558371 is about 433.6668055718. Note that the first 3 decimals are identical.

The spelling of 81558371 in words is "eighty-one million, five hundred fifty-eight thousand, three hundred seventy-one".