81815127 has 4 divisors (see below), whose sum is σ = 109086840. Its totient is φ = 54543416.

The previous prime is 81815099. The next prime is 81815141. The reversal of 81815127 is 72151818.

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 81815127 - 2²⁰ = 80766551 is a prime.

It is a super-2 number, since 2×81815127² = 13387430012052258, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81815527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13635852 + ... + 13635857.

It is an arithmetic number, because the mean of its divisors is an integer number (27271710).

Almost surely, 2^81815127 is an apocalyptic number.

81815127 is a deficient number, since it is larger than the sum of its proper divisors (27271713).

81815127 is a wasteful number, since it uses less digits than its factorization.

81815127 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27271712.

The product of its digits is 4480, while the sum is 33.

The square root of 81815127 is about 9045.1714743282. The cubic root of 81815127 is about 434.1214080550.

The spelling of 81815127 in words is "eighty-one million, eight hundred fifteen thousand, one hundred twenty-seven".