81896857 has 4 divisors (see below), whose sum is σ = 93596416. Its totient is φ = 70197300.

The previous prime is 81896827. The next prime is 81896869. The reversal of 81896857 is 75869818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81896857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81896827) 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 in 3 ways as a sum of consecutive naturals, for example, 5849769 + ... + 5849782.

It is an arithmetic number, because the mean of its divisors is an integer number (23399104).

Almost surely, 2^81896857 is an apocalyptic number.

It is an amenable number.

81896857 is a deficient number, since it is larger than the sum of its proper divisors (11699559).

81896857 is a wasteful number, since it uses less digits than its factorization.

81896857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11699558.

The product of its digits is 967680, while the sum is 52.

The square root of 81896857 is about 9049.6882266739. The cubic root of 81896857 is about 434.2659165175.

It can be divided in two parts, 818968 and 57, that added together give a square (819025 = 905²).

The spelling of 81896857 in words is "eighty-one million, eight hundred ninety-six thousand, eight hundred fifty-seven".