81178087 has 4 divisors (see below), whose sum is σ = 81228736. Its totient is φ = 81127440.

The previous prime is 81178079. The next prime is 81178091. The reversal of 81178087 is 78087118.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78087118 = 2 ⋅39043559.

It is a cyclic number.

It is not a de Polignac number, because 81178087 - 2³ = 81178079 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 (81178187) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 22839 + ... + 26152.

It is an arithmetic number, because the mean of its divisors is an integer number (20307184).

Almost surely, 2^81178087 is an apocalyptic number.

81178087 is a deficient number, since it is larger than the sum of its proper divisors (50649).

81178087 is a wasteful number, since it uses less digits than its factorization.

81178087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50648.

The product of its (nonzero) digits is 25088, while the sum is 40.

The square root of 81178087 is about 9009.8882900955. Note that the first 3 decimals coincide. The cubic root of 81178087 is about 432.9917326905.

The spelling of 81178087 in words is "eighty-one million, one hundred seventy-eight thousand, eighty-seven".