81606838 has 4 divisors (see below), whose sum is σ = 122410260. Its totient is φ = 40803418.

The previous prime is 81606827. The next prime is 81606857. The reversal of 81606838 is 83860618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 83860618 = 2 ⋅41930309.

It is a self number, because there is not a number n which added to its sum of digits gives 81606838.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20401708 + ... + 20401711.

It is an arithmetic number, because the mean of its divisors is an integer number (30602565).

Almost surely, 2^81606838 is an apocalyptic number.

81606838 is a deficient number, since it is larger than the sum of its proper divisors (40803422).

81606838 is a wasteful number, since it uses less digits than its factorization.

81606838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40803421.

The product of its (nonzero) digits is 55296, while the sum is 40.

The square root of 81606838 is about 9033.6503142417. The cubic root of 81606838 is about 433.7526923900.

The spelling of 81606838 in words is "eighty-one million, six hundred six thousand, eight hundred thirty-eight".