81992857 has 2 divisors, whose sum is σ = 81992858. Its totient is φ = 81992856.

The previous prime is 81992843. The next prime is 81992879. The reversal of 81992857 is 75829918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 41847961 + 40144896 = 6469^2 + 6336^2 .

It is a cyclic number.

It is not a de Polignac number, because 81992857 - 2¹⁵ = 81960089 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81992857.

It is not a weakly prime, because it can be changed into another prime (81992837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40996428 + 40996429.

It is an arithmetic number, because the mean of its divisors is an integer number (40996429).

Almost surely, 2^81992857 is an apocalyptic number.

It is an amenable number.

81992857 is a deficient number, since it is larger than the sum of its proper divisors (1).

81992857 is an equidigital number, since it uses as much as digits as its factorization.

81992857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 362880, while the sum is 49.

The square root of 81992857 is about 9054.9907233525. The cubic root of 81992857 is about 434.4355333198.

The spelling of 81992857 in words is "eighty-one million, nine hundred ninety-two thousand, eight hundred fifty-seven".