81686813451 has 4 divisors (see below), whose sum is σ = 108915751272. Its totient is φ = 54457875632.

The previous prime is 81686813437. The next prime is 81686813489. The reversal of 81686813451 is 15431868618.

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 81686813451 - 2⁵ = 81686813419 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81686813394 and 81686813403.

It is not an unprimeable number, because it can be changed into a prime (81686863451) 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, 13614468906 + ... + 13614468911.

It is an arithmetic number, because the mean of its divisors is an integer number (27228937818).

Almost surely, 2^81686813451 is an apocalyptic number.

81686813451 is a deficient number, since it is larger than the sum of its proper divisors (27228937821).

81686813451 is a wasteful number, since it uses less digits than its factorization.

81686813451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27228937820.

The product of its digits is 1105920, while the sum is 51.

The spelling of 81686813451 in words is "eighty-one billion, six hundred eighty-six million, eight hundred thirteen thousand, four hundred fifty-one".