81087823 has 4 divisors (see below), whose sum is σ = 81123160. Its totient is φ = 81052488.

The previous prime is 81087817. The next prime is 81087859. The reversal of 81087823 is 32878018.

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 81087823 - 2⁹ = 81087311 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 (81087323) 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, 13968 + ... + 18901.

It is an arithmetic number, because the mean of its divisors is an integer number (20280790).

Almost surely, 2^81087823 is an apocalyptic number.

81087823 is a deficient number, since it is larger than the sum of its proper divisors (35337).

81087823 is a wasteful number, since it uses less digits than its factorization.

81087823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35336.

The product of its (nonzero) digits is 21504, while the sum is 37.

The square root of 81087823 is about 9004.8777337619. The cubic root of 81087823 is about 432.8311882950.

It can be divided in two parts, 810878 and 23, that added together give a triangular number (810901 = T₁₂₇₃).

The spelling of 81087823 in words is "eighty-one million, eighty-seven thousand, eight hundred twenty-three".