81582857 has 2 divisors, whose sum is σ = 81582858. Its totient is φ = 81582856.

The previous prime is 81582833. The next prime is 81582859. The reversal of 81582857 is 75828518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 75151561 + 6431296 = 8669^2 + 2536^2 .

It is a cyclic number.

It is not a de Polignac number, because 81582857 - 2⁸ = 81582601 is a prime.

Together with 81582859, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81582859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40791428 + 40791429.

It is an arithmetic number, because the mean of its divisors is an integer number (40791429).

Almost surely, 2^81582857 is an apocalyptic number.

It is an amenable number.

81582857 is a deficient number, since it is larger than the sum of its proper divisors (1).

81582857 is an equidigital number, since it uses as much as digits as its factorization.

81582857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 179200, while the sum is 44.

The square root of 81582857 is about 9032.3229016682. The cubic root of 81582857 is about 433.7102006796.

The spelling of 81582857 in words is "eighty-one million, five hundred eighty-two thousand, eight hundred fifty-seven".