81898771 has 4 divisors (see below), whose sum is σ = 83896344. Its totient is φ = 79901200.

The previous prime is 81898693. The next prime is 81898777. The reversal of 81898771 is 17789818.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81898771 - 2⁹ = 81898259 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81898777) 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, 998725 + ... + 998806.

It is an arithmetic number, because the mean of its divisors is an integer number (20974086).

Almost surely, 2^81898771 is an apocalyptic number.

81898771 is a deficient number, since it is larger than the sum of its proper divisors (1997573).

81898771 is a wasteful number, since it uses less digits than its factorization.

81898771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1997572.

The product of its digits is 225792, while the sum is 49.

The square root of 81898771 is about 9049.7939755555. The cubic root of 81898771 is about 434.2692995471.

The spelling of 81898771 in words is "eighty-one million, eight hundred ninety-eight thousand, seven hundred seventy-one".