81678911 has 4 divisors (see below), whose sum is σ = 85230192. Its totient is φ = 78127632.

The previous prime is 81678901. The next prime is 81678941. The reversal of 81678911 is 11987618.

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 81678911 - 2¹⁰ = 81677887 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81678901) 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, 1775606 + ... + 1775651.

It is an arithmetic number, because the mean of its divisors is an integer number (21307548).

Almost surely, 2^81678911 is an apocalyptic number.

81678911 is a deficient number, since it is larger than the sum of its proper divisors (3551281).

81678911 is a wasteful number, since it uses less digits than its factorization.

81678911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3551280.

The product of its digits is 24192, while the sum is 41.

The square root of 81678911 is about 9037.6385743180. The cubic root of 81678911 is about 433.8803477837.

The spelling of 81678911 in words is "eighty-one million, six hundred seventy-eight thousand, nine hundred eleven".