81692166238 has 4 divisors (see below), whose sum is σ = 122538249360. Its totient is φ = 40846083118.

The previous prime is 81692166161. The next prime is 81692166251. The reversal of 81692166238 is 83266129618.

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

It is a super-2 number, since 2×81692166238² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20423041558 + ... + 20423041561.

It is an arithmetic number, because the mean of its divisors is an integer number (30634562340).

Almost surely, 2^81692166238 is an apocalyptic number.

81692166238 is a deficient number, since it is larger than the sum of its proper divisors (40846083122).

81692166238 is a wasteful number, since it uses less digits than its factorization.

81692166238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40846083121.

The product of its digits is 1492992, while the sum is 52.

The spelling of 81692166238 in words is "eighty-one billion, six hundred ninety-two million, one hundred sixty-six thousand, two hundred thirty-eight".