81685198 has 8 divisors (see below), whose sum is σ = 140031792. Its totient is φ = 35007936.

The previous prime is 81685193. The next prime is 81685231. The reversal of 81685198 is 89158618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81685193) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2917315 + ... + 2917342.

It is an arithmetic number, because the mean of its divisors is an integer number (17503974).

Almost surely, 2^81685198 is an apocalyptic number.

81685198 is a deficient number, since it is larger than the sum of its proper divisors (58346594).

81685198 is a wasteful number, since it uses less digits than its factorization.

81685198 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5834666.

The product of its digits is 138240, while the sum is 46.

The square root of 81685198 is about 9037.9863907842. The cubic root of 81685198 is about 433.8914797300.

It can be divided in two parts, 8168 and 5198, that added together give a triangular number (13366 = T₁₆₃).

The spelling of 81685198 in words is "eighty-one million, six hundred eighty-five thousand, one hundred ninety-eight".