81398 has 4 divisors (see below), whose sum is σ = 122100. Its totient is φ = 40698.

The previous prime is 81373. The next prime is 81401. The reversal of 81398 is 89318.

It is a happy number.

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

It is a self number, because there is not a number n which added to its sum of digits gives 81398.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 81398.

It is an unprimeable number.

81398 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20348 + ... + 20351.

It is an arithmetic number, because the mean of its divisors is an integer number (30525).

2⁸¹³⁹⁸ is an apocalyptic number.

81398 is a deficient number, since it is larger than the sum of its proper divisors (40702).

81398 is a wasteful number, since it uses less digits than its factorization.

81398 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40701.

The product of its digits is 1728, while the sum is 29.

The square root of 81398 is about 285.3033473340. The cubic root of 81398 is about 43.3382374463.

The spelling of 81398 in words is "eighty-one thousand, three hundred ninety-eight".