81898 has 4 divisors (see below), whose sum is σ = 122850. Its totient is φ = 40948.

The previous prime is 81883. The next prime is 81899. The reversal of 81898 is 89818.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 89818 = 2 ⋅44909.

It can be written as a sum of positive squares in only one way, i.e., 71289 + 10609 = 267^2 + 103^2 .

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (81899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20473 + ... + 20476.

2⁸¹⁸⁹⁸ is an apocalyptic number.

81898 is a deficient number, since it is larger than the sum of its proper divisors (40952).

81898 is a wasteful number, since it uses less digits than its factorization.

81898 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40951.

The product of its digits is 4608, while the sum is 34.

The square root of 81898 is about 286.1782661210. The cubic root of 81898 is about 43.4267936797.

It can be divided in two parts, 81 and 898, that added together give a palindrome (979).

The spelling of 81898 in words is "eighty-one thousand, eight hundred ninety-eight".