81192667687 has 4 divisors (see below), whose sum is σ = 82404498616. Its totient is φ = 79980836760.

The previous prime is 81192667657. The next prime is 81192667693. The reversal of 81192667687 is 78676629118.

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

It is a cyclic number.

It is not a de Polignac number, because 81192667687 - 2⁷ = 81192667559 is a prime.

It is a super-2 number, since 2×81192667687² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81192667657) 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, 605915364 + ... + 605915497.

It is an arithmetic number, because the mean of its divisors is an integer number (20601124654).

Almost surely, 2^81192667687 is an apocalyptic number.

81192667687 is a deficient number, since it is larger than the sum of its proper divisors (1211830929).

81192667687 is a wasteful number, since it uses less digits than its factorization.

81192667687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1211830928.

The product of its digits is 12192768, while the sum is 61.

The spelling of 81192667687 in words is "eighty-one billion, one hundred ninety-two million, six hundred sixty-seven thousand, six hundred eighty-seven".